# Math Help - Solve for X

1. ## Solve for X

9 = 40(2)^2x+1

9 = 40(2)^2x+1

3. Originally Posted by harish21
I think he wants,

$9 = 40(2)^{2x+1 }$

In which case we use basic logs.

$ln ( \frac{ 9}{40} ) = ln (2^{2x+1}) = (2x+1) ln2$

$\frac { ln ( \frac{ 9}{40} ) }{ ln2} = 2x + 1$

$\frac { ln ( \frac{ 9}{40} ) }{2 ln2} - \frac{1}{2} = x$