3^x + 5^x = 12
I have taken logs on both sides, used the power rule to get
xln3 + x ln5 = ln12
factored out x on the LHS to give x(ln3 + ln5) = ln12
x(ln15) = ln12
divided through by ln15
x = (ln12)/(ln15)
The answer I get doesnt match what I want. Where have I gone wrong please?