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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

25401.

How are animals helpful in the dispersal of seeds ?

Answer» ( A)Birds feed on juicy fruits present on trees these seeds of these fruits pass into their excreta

(B) Human eat fruits and seeds are the own away example _ orange ,mango

(C) some seeds have hooks which stick to the furs of animals example datura
25402.

Weak in mathematics So, Please help me

Answer» You can get help here in any subject.

Ask your doubt and get the help from Teachers, Seniors and friends
25403.

This lubricates your engine. A) grease B) fuel C) water D) oilE) cream

Answer»

Correct option is D) oil

25404.

HCF of 92 and 152 is(a) 4(b) 19(c) 23(d) 57

Answer»

Correct answer is (a) 4

25405.

Find the area of the triangle formed by the point(-10,-4) (-8,-1) (-3-5)

Answer»

Given (-10,-4)(-8,-1)(-3,-5)

area of triangle formula

1/2 |x1 (y2-y3)+x2 (y3-y1)+x3 (y1-y2)|

take -10 as x1,-4 as y1,-8 as x2,-1 as y2,-3 as x3,-5 as y3

than

1/2|-10 (-1-(-5))+(-8)(-5-(-4))+(-3)(-4-(-1))|

1/2|-10 (-1+5)+(-8)(-5+4)+(-3)(-4+1)|

1/2|-10 (+4)+(-8)(-1)+(-3)(-3)|

1/2|40+8+9|

1/2|57|

|28.5|

25406.

Select the option, which is the logical equivalent of the statement given below:If I like the music then I will give you a prize.1. If I do not give you a prize then I have not liked the music.2. If I give you a prize then I have liked the music.3. If the music is sweet then I will like it.4. I always give prize after listening good music.

Answer» Correct Answer - Option 1 : If I do not give you a prize then I have not liked the music.

Concepts:

If 'p' then 'q' , denoted by p → q where p and q are the hypothesis and conclusion respectively.

p → q denotes implies also,

~ p denotes not p means negation

~ q denotes not q means negation

q → p denotes converse, which means if q then p.

the converse is not true even if the implication is true.

~ p → ~ q denotes inverse, which means if not p then not q.

the inverse is not true even if the implication is true. 

~ q → ~ p  contrapositive,

the contrapositive is true if the implication is true and vice versa.

Given:

p : I like the music

q : I give you a prize

Truth table 

pqp → q~ q~ p~q → ~ p
TTTFFT
TFFTFF
FTTFTT
FFTTTT

 

Where T is true denotes positive statement and F is False denotes the negative statement,

The logical equivalence from the truth table :

Implication and contrapositive result is the same i.e, if p happens then q will happen which implies if q won't happen then p also won't happen.

Thus "If I like the music then I will give you a prize" logical equivalent statement is "If I do not give you a prize then I have not liked the music".

Hence, option 1 is the correct answer.

NOTE:

This is not an english language problem, It is about discrete mathematics proposition logic equivalence.

25407.

A farmer grows 3 crops in rotation – A, B, C. A is grown between the months Jan‐June, B between April – September and C between July‐December. Each crop takes 3 months from sowing to harvesting. At a time only crop can be grown.Farmer starts in the month of January by sowing A. If there is no gap between each crop, when would C be harvested?1. July2. August3. September4. October

Answer» Correct Answer - Option 3 : September

A farmer grows 3 crops in rotation – A, B, C.

A is grown between the months Jan‐June.

B between April – September.

C between July‐December.

AJan - June
BApril - Sept
CJuly - Dec

Each crop takes 3 months from sowing to harvesting. At a time only one crop can be grown.

Farmer starts in the month of January by sowing A. If there is no gap between each crop, then harvesting of A is March. B is sowing in the month of April and B is harvesting in the month of June and C is sowing in the month of July and harvesting in the month of September.

AJan - Feb - Mar
BApril - May - June
CJuly - Aug - Sept

So, C would be harvested in the month of September.

Hence, September is the correct answer.

25408.

He has been making money ______ since he started his new business. A) head over heels B) hand over fist C) head to foot D) ear to ear E) top to toe

Answer»

Correct option is B) hand over fist

25409.

Arbuthnot’s work is HARDLY ever real today, but, J.Bull, whom he created, is very much alive. A) barely B) always C) constantly D) happily E) cheerfully

Answer»

Correct option is A) barely

25410.

Directions for the following 2 (two) itemsConsider the given information and answer the two items that follow.No supporters of 'party X', who knew Z and supported his campaign strategy, agreed for the alliance with 'party Y'; but some of them had friends in 'party Y'.With reference to the above information, which one among the following statements must be true?1.    Some supporters of 'party Y' did not agree for the alliance with the 'party X'.2.    There is at least one supporter of 'party Y' who knew some supporters of 'party X' as a friend. 3.    No supporters of 'party X' supported Z's campaign strategy.4.    No supporters of 'party X' knew Z.

Answer» Correct Answer - Option 2 :    There is at least one supporter of 'party Y' who knew some supporters of 'party X' as a friend. 

Some supporters of 'party Y' did not agree for the alliance with the 'party X' : False because nothing is mentioned about alliance plan of 'party Y' supporters.

There is at least one supporter of 'party Y' who knew some supporters of 'party X' as a friend : True as it is mentioned clearly in the statement given in question.

No supporters of 'party X' supported Z's campaign strategy : False as it is mentioned in the statement that some supporters of 'party X' supported Z's campaign strategy.

No supporters of 'party X' knew Z : False as it is mentioned in the statement that some supporters of 'party X' knew Z.

Hence, option 2 is the correct answer.

25411.

John Bull, the nickname for the English nation, was INVENTED by a Scotsman, John Arbuthnot. A) made up B) given up C) borrowed D) shared E) removed

Answer»

Correct option is A) made up

25412.

____ is to study Chinese. A) What I plan to do B) A very difficult language C) The language that D) What language

Answer»

Correct option is A) What I plan to do

25413.

4. Let \( L \) is distance between two parallel normals of \( \frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}=1, a>b \), then maximum value of L is -(A) \( 2 a \)(B) \( 2 b \)(C) \( a+b \)(D) \( 2(a-b) \)

Answer»

option (a) is correct i.e. 2a      

cuz {a+a=2a}


25414.

The contact point of the line y = x-2 with the ellipse 3x2 + 4y2 = 24 is A. (-4,3)B. (4,-3)C.(4,3)D. None of these 

Answer»

Put \(y=x-2 \,in \,eqquation\, of \,ellipse\)

\(3x^2+4y^2=24\) we obtain

\(3x^2+4(x-2)^2=24\)

\(=3x^2+4x^2-16x+16=24\)

\(=7x^2-16x-8=0\)

\(=x=\frac{16\pm \sqrt{256+224}}{14}\)

\(x=\frac{16\pm \sqrt{480}}{14}=\frac{8\pm2\sqrt{30}}{7}\)

\(y=\frac{8+2\sqrt{30}}{7}-2\,or\,y=\frac{8-2\sqrt{30}}{7}-2\)

\(=y=\frac{2\sqrt{30}-6}{7}\,or\,y=\frac{-2\sqrt{30}-6}{7}\)

But line y = x - 2 intersects ellipse not touching it 

Hence option (D) is corret for line y = x-2.

25415.

Find the equation of ellipse whose latus rectum is half the major axis and focus is at (3,0).

Answer»

Let the major axis is 2a.

Focus is (3,0) lies on x-axis.

Hence, Major axis of ellipse lies on x-axis.

Given that   \(\frac{2b^2}{a}=\frac{2a}{2} ⇒\frac{2b^2}{a}=a\)

⇒ \(\)2b2 = a⇒  \(b^2=\frac{a^2}{2}\)     ----(i)

∴  \(e =\sqrt{1-\frac{b^2}{a^2}}\) \(= \sqrt{1 - \frac{1}{2}}\)  (From (i))

 \(e =\frac{1}{√2}\)

∴ Focus of ellipse is (ae,o) = (3,0)

⇒ ae = 3

⇒ \(a×\frac{1}{√2}=3\)

⇒ \(a=3√2\)

∴ b\(\frac{18}{2}\) = 9   (from (ii))

b = 3

Hence , equation of ellipse is 

\(\frac{x^2}{a^2}+\frac{y^2}{b^2}=1\)

⇒ \(\frac{x^2}{18}+\frac{y^2}{9}=1\)

 is equation of required ellipse.

25416.

High level knowledge and research related activities are of which sector?(a) Primary (b) Secondary(c) quarternary (d) Quinary

Answer»

High level knowledge and research related activities are Quinary sector.

25417.

Which canal is known as ‘Gateway of Pacific’?(a) Panama (b) Suez(c) Kiel (d) None of these

Answer»

Panama canal is known as ‘Gateway of Pacific’.

25418.

The practice of buying goods from other countries is known as:-(a) Trade (b) Export(c) Import (d) Foreign trade

Answer»

The practice of buying goods from other countries is known as Import.

25419.

Which of the following is traditional industry of India?(a) Cotton textile industry (b) Iron & are industry(c) Petro – chemical industry (d) None of these

Answer»

Cotton textile industry is traditional industry of India.

25420.

Problems of Human settlement in developing countries are:-(a) Agglomeration of population (b) Slums(c) Lack of drinking water (d) All of these

Answer»

Problems of Human settlement in developing countries are Agglomeration of population, Slums and Lack of drinking water. 

25421.

Government of India conferred the …………………….. With the status of Miniratna: Category- I CPSE recently?A. NTPC limitedB. Bharat Heavy Electricals LimitedC. Indian Rare Earths LimitedD. National Projects Construction Corporation Limited

Answer» Correct Answer - D
25422.

The Naval Ship on which 6 women officers of the Indian Navy successfully circumnavigated the globe?A. INSV MhadeiB. INS RajputC. INS TaringiniD. INSV Tarini

Answer» Correct Answer - D
25423.

The value of \( \int_{0}^{2 \pi}\left[\cot ^{-1} x\right] d x \) where [.] denotes greatest integer function, is....

Answer»

\(\int^{2\pi}_0[\cot^{-1}\,x]dx\)

\(= \int^{\cot 1}_0[\cot^{-1}\,x]dx\) \(+\, \int^{2\pi}_{\cot 1}[\cot^{-1}\,x]dx\)

\(= \int^{\cot 1}_0 1\,\text{dx}\) \(+\, \int^{2\pi}_{\cot 1} 0\,\text{dx}\)

(\(\because\) when \(x \in [0, \cot 1],\) \(\cot^{-1}x \in \left[\frac{\pi}{2}, 1\right]\) \(\Rightarrow [\cot^{-1} x] = 1\) and when \(x \in [\cot 1, 2\pi],\) \(\cot^{-1}x \in [1, 0]\) \(\Rightarrow [\cot^{-1} x] = 0\))

\(= [x]^{\cot 1}_0 = \cot 1 - 0 = \cot 1.\)

25424.

`int_(0)^(pi//4)"sin" x d(x- [x])` is equal to , where [x] denotes greatest integer function-A. `(1)/(2)`B. `1 - (1)/(sqrt2)`C. 1D. None of these

Answer» Correct Answer - B
We have `0 lt x lt pi//4`
`0 lt x lt 0.8`
[x] = 0
`underset(0)overset(pi//4)(int)sin x d(x-[x])`
=`underset(0)overset(pi//4)(int)sin x.d(x-0)`
=`-(cos x)_(0)^(pi//4)`
=`1 - (1)/(sqrt2)`
25425.

The solution of the primitive integral equation `(x^2+y^2)dy=x ydx`is `y=y(x)dot`If `y(1)=1`and `y(x_0)=e ,`then `x_0`is(a)`( b ) (c)2sqrt(( d ) (e)(( f ) (g) (h) e^(( i )2( j ))( k )-1( l ))( m ))( n ) (o)`(p)(b) `( q ) (r)2sqrt(( s ) (t)(( u ) (v) (w) e^(( x )2( y ))( z )+1( a a ))( b b ))( c c ) (dd)`(ee)(c)`( d ) (e)sqrt(( f )3( g ))( h )e (i)`(j)(d) `( k ) (l)sqrt(( m ) (n) (o)(( p ) (q) e^(( r )2( s ))( t )+1)/( u )2( v ) (w) (x))( y ) (z)`(aa)A. `sqrt(2 (e^(2) - 1))`B. `sqrt(2(e^(2) + 1))`C. `sqrt3 e`D. `sqrt((1)/(2) (e^(2) + 1))`

Answer» Correct Answer - C
We have
`(dy)/(dx) = (xy)/(x^(2) + y^(2))`
put y = vx
`implies (dy)/(dx) = v .1 + x (dv)/(dx)`
`v + x (dv)/(dx) = (v)/(1 +v^(2))`
`x(dv)/(dx) = (v)/(1+ v^(2))-v = (v -v-v^(3))/(1+v^(2))`
`(1+v^ (2))/(v^(3))dv = -(dx)/(x)`
`int (v^(-3) + (1)/(v))dv - int(dx)/(x)`
`(v^(-2))/(-2) + "log v " = - "log" x + C `
`-(1)/(2((y)/(x))^(2))+ "log" ((y)/(x)) = - "log"x + C `
`-(x^(2))/(2y^(2)) + "log y" = C " " ....(1)`
y(1) = 1 at x = 1 , y = 1
C - 1/2
put in (1)
`-(x^(2))/(2y^(2)) + "log y" = -(1)/(2) `
`y(x_(0)) = e`,
at x = `x_(0) , y = e`
`-(x_(0)^(2))/(2e^(2)) + 1= (-1)/(2)`
`x_(0) = sqrt3 e `
25426.

The number of real solution of the equation `tan^(-1) sqrt(x^2-3x +7) + cos^(-1) sqrt(4x^2-x + 3) = pi` isA. OneB. TwoC. ZeroD. Infinite

Answer» Correct Answer - C
as `0 le sqrt(x^(2) - 3x + 2) lt oo`
so `0 le tan^(-1) sqrt(x^(2) - 3x + 2) lt x//pi "…." (i) `
and `0 le sqrt(4x - x^(2) - 3 ) lt oo`
so `0 le cos^(-1) sqrt(4x - x^(2) - 3 ) le pi//2 "….." ( ii)`
so from (i) + (ii)
`0 le tan^(-1) sqrt(x^(2) - 3x +2 ) cos^(-1) sqrt(4x-x^(2) - 3) lt pi`
so no solution
25427.

if `f(x)=(x^2-4)|(x^3-6x^2+11x-6)|+x/(1+|x|)`then set of points at which the function if non differentiable isA. `{-2 , 2 , 1 , 3}`B. `{-2 , 0 , 3}`C. `{-2 , 2 , 0}`D. {1 , 3}

Answer» Correct Answer - D
f(x) = `(x + 2) (x-2) |(x-1) (x-2) (x-3)| + (x)/(1 + |x|)`
`(x-1) (x-2) (x-3)` is not differentiable at x = 1, 3 only.
`(x)/(1 + |x|)` is always differentiable .
25428.

Let `f(x)=(x^(2)-3x+2)(x^(3)-6x^(2)+11x-6)|+|sin(x+(pi)/(4))|` The set of points at which the function f(x) is not differentiable in `[0,2pi]` isA. `{1,2,3,(3pi)/(4),(7pi)/(4)}`B. `{1,2,3}`C. `{3,(3pi)/(4),(7pi)/(4)}`D. `{(pi)/(4),(3pi)/(4),(5pi)/(4)}`

Answer» Correct Answer - 3
`f(x)=(x-1)(x-2)|(x-1)(x-2)(x-3)|+|sin (x+pi//4)|`
Where (x-1)(x-2)(x-3) is not differentiable at x=3 `sin(X+pi//4))` is not differentiable at `x+(pi)/(4)=pi,2pi`
`implies x=(3pi)/(4),(7pi)/(4)`
25429.

In the interval `[-pi/2,pi/2] `the equation `log_(sin theta)(cos 2 theta)=2` hasA. no solutionB. a unique solutionC. two solutionD. infinitely many solutions

Answer» Correct Answer - 2
`because -1 le sin theta le 1 "here"
25430.

Let a, b, c ∈ R, a ≠ 0.Statement–1 : Difference of the roots of the equation ax2 + bx + c = 0 = Difference of the roots of the equation – ax2 + bx – c = 0Statement–2 : The two quadratic equations over reals have the same difference of roots if product of the coefficient of the two equations are the same.(A) Statement – 1 is True, Statement – 2 is True; Statement – 2 is a correct explanation for Statement – 1. (B) Statement – 1 is True, Statement – 2 is True; Statement – 2 is NOT a correct explanation for Statement – 1.(C) Statement – 1 is True, Statement – 2 is False. (D) Statement – 1 is False, Statement – 2 is True

Answer»

Correct option (C) Statement – 1 is True, Statement – 2 is False.

Explanation:

Statement–I is true, as Difference of the roots of a quadratic equation is always D , D being the discriminant of the quadratic equation and the two given equations have the same discriminant.

Statement – II is false as if two quadratic equations over reals have the same product of the coefficients, their discriminents need not be same.

Hence (c) is the correct answer. 

25431.

Find the BD on ? 1015, payable after 3 months at 6% p.a.

Answer»

Given F = 1015, 

F=1015, t = 3/12 year, r = 6/100 = 0.06, BD = ? 

BD = Ftr = 1015 x 3/12 × 0.06 = 15.22

25432.

If sin A = 3/5, cos B = 4/5 find sin(A + B) and cos(A – B). Where A and B are acute angles.

Answer»

Given sin A = 3/5, cos B = 4/5

⇒ cos A = 4/5 & sin B = 3/5

∵ sin2A + cos2A = 1

(i) sin(A + B) = sinA cosB + cosA sinB 

= 3/5. 4/5 + 4/5.3/5 = 24/25

(ii) cos(A – B) = COSA COSB + sinA sinB

= 4/5.4/5 + 3/5.3/5 = 16/25 + 9/25 = 25/25 = 1

25433.

Show f(x) defined by f(x) = {((x2 - 25)/(x - 5) when  x ≠ 5),(10, when x = 5) is continuous at x = 5

Answer»

Also f(x) at x = 5 is 10; i.e, f(5) = 10 

Here lim(x5) f(x) = f(5) = 10.

∴ the function f(x) is continuous at x = 5

25434.

For what value of `x` is the matrix `A=[(0,1,-2),(1,0,3),(x,3,0)]` a skew-symmetric matrix?

Answer» `A = [[0,1,-2],[-1,0,3],[x,-3,0]]`
`:. A^T = [[0,-1,x],[1,0,-3],[-2,3,0]]`
Now, for a matrix `A` to be a skew-symmetric matrix,
`A = -A^T`
Here, `-A^T = [[0,1,-x],[-1,0,3],[2,-3,0]]`
`:. [[0,1,-2],[-1,0,3],[x,-3,0]] =[[0,1,-x],[-1,0,3],[2,-3,0]]`
So, `-x = -2 and x = 2`
`:.` For `x = 2`, given matrix will be skew symmetric.
25435.

Sketch the graph of `y=|x+3|`and evaluate thearea under the curve `y=|x+3|`above x-axisand between `x=6` to `x=0.`

Answer» `y = x+3`, when `x ge -3`
`y = -x-3`, when `x lt -3`
So, now we can draw the graph using these two equations.
Please refer to video to see the graph.
We have to find the area between `x = -6` to `x = 0`.
From the graph, we can see that required area is area of two right angle triangles.
`:.` Required Area `= 2(1/2*3*3) = 9` square units.
25436.

Prove the following:`cos^(-1)((12)/(13))+sin^(-1)(3/5)=sin^(-1)((56)/(65))`

Answer» Let `cos^-1(12/13) = x`
Then, `cosx = 12/13`
`:. sinx = sqrt(1-(12/13)^2) = sqrt(25/169) = 5/13`
`:. x = sin^-1(5/13)`
`:. L.H.S. = cos^-1(12/13) +sin^-1(3/5) = sin^-1(5/13) +sin^-1(3/5)`
We know, `sin^-1A+sin^-1B = sin^-1(Asqrt(1-B^2)+Bsqrt(1-A^2))`
So,our expression becomes,
`= sin^-1(5/13sqrt(1-(3/5)^2)+3/5sqrt(1-(5/13)^2))`
`=sin^-1(5/13*4/5+3/5*12/13)`
`=sin^-1(4/13+36/65)`
`=sin^-1(56/65) = R.H.S.`
25437.

Write the vector equation of the following line:`(x-5)/3=(y+4)/7=(6-z)/2`

Answer» Let `(x-5)/3 = (y+4)/7 = (6-z)/2 = lambda`
Then,
`=>x = 3lambda+5`
`=>y = 7lambda-4`
`=>z = -2lambda+6`
`:. vecr = xhati+yhatj+zhatk`
`=>vecr = (3lambda+5)hati+(7lambda-4)hatj+(-2lambda+6)hatk`
`=>vecr = (5hati-4hatj+6hatk)+lambda(3hati+7hatj-2hatk)`,which is the required vector equation.
25438.

Show that the points A(a, b + c), B(b, c + a) and C(c, a + b) are collinear.

Answer»

Given points are A(a, b + c), B(b, c + a) and C(c, a + b). 

We know that area of triangle whose vertices are (x1, y1), (x2, y2) and (x3, y3) is given by \(\frac{1}{2}\) [x1 (y2 − y3) + x2 (y3 − y1 ) + x3 (y1 − y2)]. 

∴ Area of triangle formed by the points A, B and C 

= \(\frac{1}{2}\) [a((c + a) − (a + b)) + ((a + b) − (b+ c)) +c ((b + c)– (c + a))] 

= \(\frac{1}{2}\) [a(c – b) + b(a – c) + c(b – a)] 

= \(\frac{1}{2}\) [ac – ab + ba – bc + cb – ca] 

= \(\frac{1}{2}\) [ac – ca + ba – ab + cb – bc] 

= \(\frac{1}{2}\) [ac – ac + ba – ba + cb – cb] (∵ ac = ca & ba = ab & bc = cb) 

= \(\frac{1}{2}\) × 0 = 0. 

Area of triangle formed by the point A, B and C is zero which is condition that A, B & C are collinear. 

Hence, points A(a, b + c), B(b, c + a), and C(c, a + b) are collinear.

25439.

From the following matrix equation, find the value of `x:[[x+y,4],[-5,3y]]=[[3,4],[-5,6]]`

Answer» Here,`[[x+y,4],[-5,3y]] = [[3,4],[-5,6]]`
`=>x+y = 3->(1)`
`=>3y = 6=>y = 2`
Putting value of `y` in (1),
`=>x+2 = 3=>x = 3-2`
`=>x = 1`
25440.

Find the value of x, from the following: `|(x,4),(2,2x)|=0`

Answer» `|[x,4],[2,2x]| = 0`
Expanding the determinant,
`x(2x)-4(2) = 0`
`=>2x^2-8 = 0`
`=>2x^2 = 8`
`=>x^2 = 4`
`=>x = 2 or x = -2`
25441.

The set of values of k, for which A =\(\begin{bmatrix} k& 8 \\[0.3em] 4 & 2k \end{bmatrix}\)is a singular matrix is :A = [(k,8)(4,2k)](a) {4}(b) {- 4}(c) {- 4, 4}(d) {0}

Answer»

Option : (c)

As A is singular matrix

⇒ |A| = 0 

⇒ 2k2 − 32 = 0 

⇒ k = ±4

25442.

What is the nature of the roots of the quadratic equation 4x2 – 12x – 9 = 0?

Answer»

b2 -4ac = 122 -4(-9)4

Roots are real and unequal 

= 144 +144 = 228 >0

25443.

Prove the following:`tan[pi/4+1/2cos^(-1)(a/b)]+tan[pi/4-1/2cos^(-1)(a/b)]=(2b)/a`

Answer» Let `1/2cos^-1(a/b) = x`
Then, `a/b = cos2x->(1)`
Now,
`L.H.S. = tan(pi/4+1/2cos^-1(a/b))+tan(pi/4-1/2cos^-1(a/b))`
`=tan(pi/4+x)+tan(pi/4-x)`
`=(1+tanx)/(1-tanx)+(1-tanx)/(1+tanx)`
`=((1+tanx)^2+(1-tanx)^2)/(1-tan^2x)`
`=(1+tan^2x+2tanx+1+tan^2x-2tanx)/(1-tan^2x)`
`=(2(1+tan^2x))/(1-tan^2x)`
We know, `tan^2x = sec^2x-1`
So, our expression becomes,
`=(2sec^2x)/(2-sec^2x)`
`=(2/cos^2x)/(2-1/cos^2x)`
`=2/(2cos^2x-1)`
`=2/(cos2x)`
`=(2)/(a/b)` (From (1))
`=(2b)/a = R.H.S.`
25444.

Write the value of the following determinant `|(a-b,b-c,c-a),(b-c,c-a,a-b),(c-a,a-b,b-c)|`

Answer» `|[a-b,b-c,c-a],[b-c,c-a,a-b],[c-a,a-b,b-c]|`
Applying `R_1->R_1+R_2+R_3`
`=|[0,0,0],[b-c,c-a,a-b],[c-a,a-b,b-c]|`
Here, all elements in first row are `0`.
`:.` Value of the determinant is `0`.
`=>|[a-b,b-c,c-a],[b-c,c-a,a-b],[c-a,a-b,b-c]| =0`
25445.

Prove that tangents drawn from an external point are equal in length. 

Answer»

Length = √op2 -r2 = √(132 -52) = 12 cm

25446.

Let f ∶ N→ N such that f(x) = 2 for all . x \(\in\) N Show that f is one-one and into.

Answer»

We have function defined on such that f(x) = 2x ∀ x∊N . 

Let x1, x2 ∊ N such that x1 ≠ x2

⇒ 2x1 ≠ 2x2 (By multiplying by 2 both sides of equation. ) 

⇒ f(x1) ≠ f(x2). 

Hence, different elements have different images under the function . 

This implies each element of connected with different elements (even numbers) of under the function , therefore, function f(x) is one-one function. 

Let f(x) = 3 ∊ N. 

⇒ 2x = 3 ⇒ x = \(\frac{3}{2}\)∉ N . 

Hence, 3 ∊ N does not have pre-image under the function f, therefore, function f(x) is an into function. 

No odd numbers have pre-image of function . 

Hence, function f ∶ N → N such that f(x) = 2x is one-one and into function.

25447.

Let* be a binary operation on `N`given bya*b = HCF`(a , b) a , b Ndot`Write thevalue of 22*4.

Answer» Here, `a**b = HCF(a,b) a,b in N`
`:. 22**4 = HCF(22,4)`
`=>22 = 2**11 and 4 = 2**2`
Here, common factor is `2`. So,HCF is `2`.
`:. 22**4 = 2`
25448.

If `x^y=e^(x-y),`show that `(dy)/(dx)=(logx)/({log(x e)}^2)`

Answer» `x^y = e^(x-y)`
Taking log both sides,
`log(x^y) = log(e^(x-y))`
`=>ylogx = (x-y)loge`
As `log e = 1`,
`=>ylogx+y = x`
`=>y(1+logx) = x`
`y = x/(1+logx)`
`dy/dx = ((1+logx)1-x(1/x))/(1+logx)^2`
`=>dy/dx = (1+logx-1)/(loge+logx)^2`
`=>dy/dx = logx/(log(xe))^2`
25449.

Let = {1, 2, 3} and = {(1, 1), (2, 2), (3, 3), (1, 3), (3, 2), (1, 2)}. Then verify that is transitive or not.

Answer»

Let set = {1, 2, 3}.

And relation on set is defined as = {(1, 1), (2, 2), (3, 3), (1, 3), (3, 2), (1, 2)}. 

Since, if there is any (a, b) ∊ R and (b, c) ∊R for a,b,c ∊ R, then (a, c) ∊ R.

Hence, relation R is a transitive relation on set A.

25450.

Find the value of x for which (8x + 4), (6x-2) and (2x+7) are in A.P.

Answer»

2(6x -2) = (8x +4) (2x +1)

12x -4 = 10x +11

2x = 15x =15/2