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Solve by factoring 12=-7x-x^2

Solve by factoring 12=-7x-x^2-example-1
User Pio
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4 votes

Answer:

C

Explanation:

12 = - 7x - x² ( add x² to both sides )

x² + 12 = - 7x ( add 7x to both sides )

x² + 7x + 12 = 0 ← in standard form

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

the factors are + 4 and + 3 , then

(x + 4)(x + 3) = 0 ← in factored form

equate each factor to zero and solve for x

x + 4 = 0 ⇒ x = - 4

x + 3 = 0 ⇒ x = - 3

solutions are x = - 4 and x = - 3

with a = - 4 and b = - 3

then

a² + b² + a + b

= (- 4)² + (- 3)² + (- 4) + (- 3)

= 16 + 9 - 4 - 3

= 25 - 7

= 18

User Xknozi
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