How do you solve 3^(x-8)=8^x?

1 Answer
Mar 16, 2016

x~~-8.96

Explanation:

1. Since the left and right sides of the equation do not have the same base, start by taking the log of both sides.

3^(x-8)=8^x

log(3^(x-8))=log(8^x)

2. Use the log property, log_color(purple)b(color(red)m^color(blue)n)=color(blue)n*log_color(purple)b(color(red)m), to simplify both sides of the equation.

(x-8)log3=xlog8

3. Expand the brackets.

xlog3-8log3=xlog8

4. Group all like terms together such that the terms with the variable, x, are on the left side and 8log3 is on the right side.

xlog3-xlog8=8log3

5. Factor out x from the terms on the left side of the equation.

x(log3-log8)=8log3

6. Solve for x.

x=(8log3)/(log3-log8)

color(green)(|bar(ul(color(white)(a/a)x~~-8.96color(white)(a/a)|)))