Question

What the answer to this problem f(x)=-4x^2+12x-9

Answer 1

We are given the function;

$f(x)=-4x^2+12x-9$

The input of this function as it is, is x. To evaluate the function at any given output we would simply replace/substitute the value of x with the value provided.

If for example, we are given the function and we have to evaluate its value at f(3), what we will simply do is replace x with two in the function. This is shown below;

$\begin{gathered} f(x)=-4x^2+12x-9 \\ f(3)=-4(3)^2+12(3)-9 \\ f(3)=-4(9)+36-9 \\ f(3)=-36+36-9 \\ f(3)=-9 \end{gathered}$

Therefore, the value of the function at f(3) is -9.

This is basically the procedure we shall use when evaluating a function at any given output value.