How do you solve # 16^(x - 4) = 3^(3 - x)#?

1 Answer
Mar 16, 2016

#x~~3.72#

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.

#16^(x-4)=3^(3-x)#

#log(16^(x-4))=log(3^(3-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-4)log16=(3-x)log3#

#3#. Expand the brackets.

#xlog16-4log16=3log3-xlog3#

#4#. Group all like terms together such that the terms with the variable, #x#, are on the left and the ones without on the right.

#xlog16+xlog3=3log3+4log16#

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

#x(log16+log3)=3log3+4log16#

#6#. Solve for #x#.

#x=(3log3+4log16)/(log16+log3)#

#color(green)(|bar(ul(color(white)(a/a)x~~3.72color(white)(a/a)|)))#