The number of real solutions cos(e^x)=2^x + 2^-xcos(ex)=2x+2x is ?

1 Answer
Feb 25, 2018

See below.

Explanation:

2^x+2^-x2x+2x is an even function with minimum at x = 0x=0

or 2 le 2^x+2^-x22x+2x

also we know that

-1 le cos(y) le 11cos(y)1

and the conclusion is that

cos(y)cos(y) and 2^x+ 2^-x2x+2x does not intercept so no real solution is possible for

cos(e^x)=2^x + 2^-xcos(ex)=2x+2x