Question

What are the roots of x^2+7x+12
A:6&2
B:-6&-2
C:3&4
D:-3&-4​

Answer 1

D -3, -4.

Explanation:

x^2 + 7x +12 = 0

12 = 3*4 and 7 = 3 + 4 so we write:

(x + 3)(x + 4) = 0

x + 3 = 0 , x + 4 = 0

So x = -3, -4.

Answer 2

D

Explanation:

x² + 7x + 12

to find the roots equate the expression to zero

x² + 7x + 12 = 0

Consider the factors of the constant term (+ 12) which sum to give the coefficient of the x- term (+ 7)

the factors are + 3 and + 4 , since

3 × 4 = 12 and 3 + 4 = 7 , then

(x + 3)(x + 4) = 0 ← in factored form

equate each factor to zero and solve for x

x + 3 = 0 ⇒ x = - 3

x + 4 = 0 ⇒ x = - 4