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)|)))#