By making the substitution u=7^x and using part a, derive a hidden quadratic equation

Question

7^(2x-1) +4×7^(x-1) -1/14 =0

and hence find all of the solutions to the above equation.

Answer 1

so, did you do the substitution?
7^(2x) = u^2

the rest is just numbers, so you have a quadratic equation with a bunch of 7's floating around.

Answer 2

I don't understand how you would do that