Question

What will be the value of k if equations 3x-y=4 and kx+5y=3 have unique solution .
(A) K=15
(B)k≠15
(C) k≠-15
(D) None of these.​

Answer 1

Ans: C

let 3x-y=4 .............. (1)

and kx+5y = 3 ...........(2)

As we know for UNIQUE SOLUTION

a1/a2 ≠ b1/b2

Here, In (1) a1 = 3 and b1= -1 and in (2) a2 = k and b2=5

3/ k ≠ -1/5

by cross multiplying

k≠-15