SECTION : B11.If the 10thterm of an A.P. is 47 and its 1st term is 2, – InterviewSolution

1.	SECTION : B11.If the 10thterm of an A.P. is 47 and its 1st term is 2, find the sum of its first 15 terms.
Answer» First term a = 2let common difference = dTn = a + (n-1)d47 = 2 + (10-1)dd = 5Sn = n[2a + (n-1)d]/2S15 = 15[22 + 145]/2S15 = 15*37 = 555

Discussion

No Comment Found

Related InterviewSolutions

The bisector of an exterior angle at the vertex of an isosceles triangle isparallel to its base. State and prove its converse.
( x - 5 ) ( x - 6 ) = \frac 25 ( 24 ) ^ 2
Write any two rational numbers which are between 2.3 and 2.4.
3. State exterior angle property of a triangle
Mathematics for Class 7and name2. Given below are pairs of congruentriangles. State the property of congruencethe congruent triangles in each case.Q.50 50В 70.60 60
8D180 (linear pair property),Hence, AD bisects BC at right angles.EXERCISE 9(B). Given below are pairs of congruent triangles. State the property of congruence and name thecongruent triangles in each case
10. State the property illustrated in the following.-5 9 9,56 24 24X--=
3. Write two rational numbers between :NE(b)- and -COIN
mine the longest tape which can be used to measure exactly the lengths 7 m
Find the general solution of the equation: sin x + sin 3x + sin 5x-0.+ sin 3x sin 5x 0