Daniel B. answered 01/23/21
A retired computer professional to teach math, physics
Let P(x) be the polynomial in the picture.
From the picture we use the facts that
P(-2) = 0
P(-1) = 8
P(1) = 0
Question 1)
P(x) = (x+1)Q(x) + R(x)
for some polynomials Q(x) and R(x), where R(x) is of degree 0.
Substituting x = -1:
P(-1) = (-1+1)Q(-1) + R(-1)
8 = R(-1)
Since R(x) is a constant, it is the constant 8.
Question 2) and 3)
Remainder is 0, because both (x+2) and (x-1) are factors, because both -2 and 1 are roots.