Question

Find k if (x+3) is a factor of 3x^2+kx+6

Answer 1

Use factor theorum: If $(x+3)$ is a factor of $p(x)=3x^2+kx+6$ then $p(-3)=0$;$\\p(-3)=3(-3)^2+k(-3)+6 =27-3k+6=33-3k=0\\\Rightarrow k=11$