I'm not sure how to solve the equation 5^x-12*(5^-x)-1=0
multiply all terms by 5^x
5^2x-12-5^x=0
let u=5^x
then u^2-u-12=0
(u-4)(u-3)=0
solve for u, substite back in, solve for x.
5^2x-12-5^x=0
let u=5^x
then u^2-u-12=0
(u-4)(u-3)=0
solve for u, substite back in, solve for x.