Question

Find the value of k if: (-2)ᵏ+¹ × (-2)³ = (-2)⁷

Answer 1

Answer:

Correct option is

A

k=0

C

k=3

The given equation is 

(k+1)x2−2(k−1)x+1=0 

comparing it with ax2+bx+c=0 we get

a=(k+1),b=−2(k−1) and c=1

∴ Discriminant,

D=b2−4ac=4(k−1)2−4(k+1)×1

=4(k2−2k+1)−4k−4

⇒4k2−8k+4−4k−4=4k2−12k

Since roots are real and equal, so

D=0⇒4k2−12k=0⇒4k(k−3)=0

⇒ either k=0 or k−3=0⇒4k(k−3)=0

Hence, k=0,3.

Answer 2

Taking power only,

K+1*3=7
Or, K+3=7
Or,K=7-3
Or, k=4