Question

p(x)=x^2-3xfind: p(-3)find p(x)=4

Answer 1

The given function is

$p(x)=x^2-3x$

The expression p(-3) means we have to evaluate the polynomial when x = -3.

$p(-3)=(-3)^2-3(-3)=9+9=18$

Therefore, p(-3) = 18.

On the other hand, p(x) = 4 means we have to evaluate the polynomial when p(x) = 4.

$4=x^2-3x$

Then, we solve for x.

$x^2-3x-4=0$

To find the solutions, we have to find two numbers whose product is 4 and which difference is 3. Those numbers are 4 and 1.

$\begin{gathered} (x-4)(x+1)=0 \\ x-4=0\rightarrow x=4 \\ x+1=0\rightarrow x=-1 \end{gathered}$

Therefore, when p (x) = 4, x = 4 and x = -1.