1.

For which value(s) of λ , do the pair of linear equationsλx + y = λ2 and x + λy = 1 have(i) no solution?(ii) infinitely many solutions?(iii) a unique solution?

Answer»

The given pair of linear equations is

λx + y = λ2 and x + λy = 1

a1 = λ, b1= 1, c1 = – λ2

a2 =1, b2=λ, c2=-1

The given equations are;

λ x + y – λ2 = 0

x + λ y – 1 = 0

Comparing the above equations with ax + by + c = 0;

We get,

a1 = λ, b1 = 1, c1 = – λ 2;

a2 = 1, b2 = λ, c2 = – 1;

a1 /a2 = λ/1

b1 /b2 = 1/λ

c1 /c2 = λ2

(i) For no solution,

a1/a2 = b1/b2≠ c1/c2

i.e. λ = 1/ λ ≠ λ2

so, λ 2 = 1;

and λ 2 ≠ λ

Here, we take only λ = – 1,

Since the system of linear equations has infinitely many solutions at λ = 1,

(ii) For infinitely many solutions,

a1/a2 = b1/b2 = c1/c2

i.e. λ = 1/ λ  = λ2

so λ = 1/ λ gives λ = + 1;

λ = λ 2 gives λ = 1,0;

Hence satisfying both the equations λ = 1 is the answer.

(iii) For a unique solution,

a1/a2 ≠ b1/b2

so λ ≠1/ λ

hence, λ2 ≠ 1;

λ ≠ + 1;

So, all real values of λ except +1



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