Question

Fill in the missing number to complete the factorization: x3+x2-21x-45= (x+3)(x-5)(x+_)

Answer 1

Answer:

The third factor is [X+(-7)]

Answer 2

Let three zeroes -3, 5, and γ(solution we don't know).

We know that $x^3+x^2-21x-45=(x+3)(x-5)(x-\gamma)$.

Then,

• $-3+5+\gamma=-1$,
• $-15-3\gamma+5\gamma=-21$,
• $-15\gamma=-45$.

∴The value of γ is -3.

$x^3+x^2-21x-45=(x+3)^2(x-5)$

The underlined part is 3.