Question

For the function f(x)=x2−8x+11, find x when f(x)=−4.(Use a comma to separate multiple solutions.)

Answer 1

Given function:

$f(x)=x^2-8x+11$

Finding x when f(x) = -4

$x^2-8x+11=-4$$\begin{gathered} x^2-8x+15=0 \\ x^2-5x-3x+15=0 \end{gathered}$$\begin{gathered} x(x-5)-3(x-5)=0 \\ (x-3)(x-5)=0 \\ x=3,5 \end{gathered}$

Thus, the value of x is 3 and 5.