Question

Find f(a-4) when f(x)= x²-3

Answer 1

The given function is

`f(x)=x^2-3`

The expression f(a-4) means we have to evaluate the function when x = a-4.

`f(a-4)=(a-4)^2-3`

Now, we solve the power using the following rule.

`(a-b)^2=a^2-2ab+b^2`

Where b = 4, and a = a.

`\begin{gathered} f(a-4)=a^2-2(a)(4)+4^2-3 \\ f(a-4)=a^2-8a+16-3 \\ f(a-4)=a^2-8a+13 \end{gathered}`

Therefore, the final expression is

`f(a-4)=a^2-8a+13`