Question

The equation $2^{2x}+(a-1)2^{x+1}+a=0$ has roots reciprocal to each, then set of values of 'a' is

• A. a < 0
• B.
• C.
• D.

Answer 1

The correct option is D

Let $2^x=t$

f(t) = $t^2$+ 2(a-1) t + a = 0 , has positive roots reciprocal to each other

then :f(1) $<$ 0 $\Rightarrow$ 3a $<$ 1 $\Rightarrow$ a $<$ $\frac{1}{3}$