Question

Simplify: (x – 4)(x2 – 3x – 9)
A x3 + x2 – 3x – 36
B x3 – 7x2 – 21x + 36
C x3 – 7x2 + 3x + 36
D x3 – 4x2 – 12x + 36

Answer 1

Hi there!

(x - 4) (x² - 3x - 9)

⇒ (x³ - 3x² - 9x) + (- 4x² + 12x + 36)

⇒ x³ - 3x² - 9x - 4x² + 12x + 36

⇒ x³ - 7x² + 3x + 36

Hence,
$\textbf{Option \:C.}$ x³ - 7x² + 3x + 36 is Correct.

~ Hope it helps!

Answer 2

$\sf Hello!$

$\sf (x - 4).(x^{2} - 3x - 9)$

⇒ $\sf x^{3} - 3x^{2} - 9x - 4x^{2} + 12x + 36$

⇒ $\sf x^{3} - 3x^{2} - 4x^{2} - 9x + 12x + 36$

⇒ $\sf x^{3} - 7x^{2} + 3x + 36$

$\sf Hence,$

$\sf C.\: \sf x^{3} - 7x^{2} + 3x + 36 \:is \:the \:required \:simplified\: form.$

~ $\sf iCarl$