Evaluate of function h (3a) = x^4+2a^2+4

If you would like to evaluate function h (x) = x^4 + 2 * a^2 + 4 when x = 3a, you can do this using the following steps:

x = 3a

h (x) = x^4 + 2 * a^2 + 4

h (3a) = (3a) ^4 + 2 * a^2 + 4 = 3^4 * a^4 + 2 * a^2 + 4 = 81 * a^4 + 2 * a^2 + 4

The correct result would be h (3a) = 81 * a^4 + 2 * a^2 + 4.