Question

Which of the following is the correct factorization of the trinomial below?

-7x2 + 5x + 12

A. (-7x + 12)(x - 1)
B. 7(x + 1)(-x + 12)
C. -7(x - 6)(x + 1)
D. -1(7x - 12)(x + 1)

Answer 1

D: Is the correct Answer

Answer 2

-1(7x+12)(x+1)

Explanation:

1) Find out which two integer numbers whose product result in -84 and whose sum is -5?

-7x² +5x +12= 0

Product ( )*( )= -84

And Sum ( )+( )= 5

12 * -7 = -84 and 12 +(-7) = 5

2) We now can rewrite the above trinomial as

-7x²+12x-7x-12=0

3) Group them, highlight the MCD and rewrite it as a product.

x(7x+12) -1(7x-12)=0 Maximum Common Divider in evidence

x(7x+12) -1(7x-12)=0 Common Factor in bold multiplied by -1

-1(7x-12)(x+1) The Second term was divided by -1

-1(7x+12)(x+1)=0

4) Test it, to check your work

-1(7x+12)(x+1)

-1[7x²-5x-12]

-7x²+5x+12