Algebra math work help

Question

when dividing x^3+nx^2+4nx-6 by x+3, the remainder is -48. what is the value of n

Answer 1

when dividing x^3+nx^2+4nx-6 by x+3, the remainder is -48. what is the value of n

Plug in the value of x=-3 in x^3+nx^2+4nx-6

(-3)^3+n(-3)^2+4n(-3)-6=-48 solve for n

-27+9n-12n-6=-48

-3n=-15

n=5

x^3 +5x^2+20x-6 when divided by x+3, the remainder is -48