Question

Fill in the missing number to complete the factorization:

x 3 + x 2 - 21x - 45

Answer 1

$</p><p> {x}^{3} + {x}^{2} - 21x - 45 \\ let \: (x + 3) \: be \: the \: factor \: of \: the \: given \\ so \: x = - 3 \\ - {3}^{3} + { - 3}^{2} - 21 \times - 3 - 45 \\ - 27 + 9 + 63 - 45 \\ - 72 + 72 \\ = 0 </p><p>$