Question

If p(x)=Xsquare+kx+9 and p(-2)=4,then k=?

Answer 1

Given function is $p(x)=x^2+kx+9$ and p(-2)=4.

p(-2)=4 means if we plug x=-2 then value of p(x) becomes 4. So let's plug these values into given function.

$p(x)=x^2+kx+9$

$4=(-2)^2+k(-2)+9$

$4=4-2k+9$

$4=-2k+13$

$4-13=-2k$

$-9=-2k$

$\frac{-9}{-2}=k$

4.5=k

Hence final answer is k=4.5.