Polynomial PSAT Practice Test Question

p(x) = 3(x^2 + 10x + 5) – 5(x – k)
In the polynomial p(x) defined above k is a constant. If p(x) is divisible by x what is the value of k?
A) -3 B)-2 C)0 D)3
And please explain how you got the answer like what method you went through to get the answer.