solve the exponential equation?

Question

2^(x+3) + 2^x = 18 And 3^2x - 10(3^x) + 9 = 0

Answer 1

For the first problem,

2^(x+3) = (2^x)( 2^3) = 8 (2^x)

Now combine terms on the left side.

For the second problem, note that

3^(2x) = (3^x)²

Let y = 3^x. Then you have a quadratic equation for y. Solve it for y, then set 3^x equal to each y-solution and solve for x.