Kayla H.

asked • 03/04/21# 5(x- _) (x+4) = 5x²+_x-60

What do the blanks equal?

## 4 Answers By Expert Tutors

Hello, Kayla,

**5(x- _) (x+4) = 5x²+_x-60**

The first blank needs a vaiue such that when it is multiplied by 4, the result is -30. 15 is what we need. But there is a 5 in front of the expression, so the value inside should be a 3.

**5(x- 3) (x+4) = 5x²+_x-60**

**Multiply the two expressions and we'll find**

**(5x- 15) (x+4) = 5x²+5x-60**

**Bob**

Put z in for the blank.

Expand the Left SIde to get: 5x^{2}-5xz+20x-20z is identically equal to 5x^{2}+zx-60

Immediately z must be 3

5(x-3)(x+4)= 5x^{2}+5x-60 and this checks with the x term from above.

divide by 5 to get

(x-a )(x+4) = x^2 + bx/5 -12

-4a = -12 constant terms' product = -12

a = 3

(x-3)(x+4) = x^2 +x -12 b/5 = 1, b=5

5(x-3)(x+4) = 5x^2 +5x + 60

Mark M. answered • 03/04/21

Retired college math professor. Extensive tutoring experience.

(5)(-3)(4) = -60

5(x-3)(x+4) = 5(x^{2} + x - 12) = 5x^{2} + 5x - 60

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03/06/21