Substitute 4 for x in the expression. After substituting for x, your new problem will be: 2(4)^2 - 30.
Solve the exponents first, so now you will have 2(16) - 30.
Multiply 2 times 16. 2 * 16 = 32, so now your problem should look like: 32 - 30.
Subtract to get your final answer of 2.
f(4) = 2
