Question

Looking for an answer to all of the following in the picture but especially question 7

Answer 1

Given

$3x^3+10x^2-x-12$

Answer

X-3 is factor if for x =3 , above expression is 0

$\begin{gathered} 3(3)^3+10(3)^2-3-12 \\ 81+270-15=336\ne0 \\ \end{gathered}$

So x-3 is not a factor,