Question

David correctly factored the expression m^2 -12m - 64.

Which expression did he write?
(1) (m - 8)(m - 8) (3) (m - 16)(m + 4)
(2) (m - 8)(m + 8) (4) (m +16)(m - 4)
Explain why

Answer 1

(3) (m - 16)(m + 4)

Explanation:

Given the expression:

m^2 -12m - 64.

Using quadratic formula:

`m = (-b \pm √(b^2 - 4(a)(c)))/(2(a))`

`m = (12 \pm √((-12)^2 - 4(1)(-64)))/(2(1))`

`m = (12 \pm 20)/(2)`

`m_1 = (12 + 20)/(2)`

`m_1 = 16`

`m_2 = (12 - 20)/(2)`

`m_2 = -4`

Then, the factored expression is:

(m - 16)(m + 4)