Find the minimum value of 9^x - 2 \cdot 3^x + 1 over all real numbers x.
The minimum value is 5/9.
read it as 9^x - 2(3^x) + 1, so the minimum value is 0 9^0 - 2(3^0) + 1
1 - 2(1) + 1
2 - 2
0