# Math Help - logarithm double x

1. ## logarithm double x

solve for x

5^x = 4 ^ (x+1)

2. Originally Posted by aeroflix
solve for x

5^x = 4 ^ (x+1)
Take logarithm of each side..

3. You could use logarithms directly but I fancy using the laws of indices and of logarithms for a change

$5^x = 4 \cdot 4^x$

$x\,\ln(5) = \ln(4) + x\,ln(4)$

Simplify to find x. If your answer book uses $\ln(2)$ then recall that $4=2^2$