8th grade?? math problem answer please?

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5h^2 + 17h - 12 = (5h - 3)(h + 4)

A. (h + 4)...Show more

You need to crunch the possible solutions:

If its A (h+4), the only possible other factor would be (5h-3). That solution works. Do the math by multiplying (h+4) X (5h-3). You get 5h^2+17h-12.

We only need to stop there...but to make my point.
If its B (5h+3), the only other factor would be (h-4)...that gives 5h^2-17h-12
...and so on for C, D.
The trick is to look at the first set of numbers in the polynomial (5h^2). That gives you the first clue.
Then look at the last expression (-12). Then quickly crunch the multiplication to get the middle part and see if it matches (+17h)...Show more

5h^2+17h-12 = (h+4)(5h-3)
Ah^2+Bh-C

To find factors, multiply A and C = 60
Find two numbers that multiply to 60 but add up to B (which is 17)
12*5 = 60
12+5 = 17

Answer: A...Show more

Factoring this one is messy...
There's only one way to factor 5.

(5h )(h )
12 is negative so one factor will be positive and one will be negative

let's try 4 and 3 (to be honest, this is a bit of experience or trial and error and realizing you need a big positive number)
5*4=20-3=17
the 4 is positive and 3 is negative

(5h-3)(h+4)
the only match is A...Show more

Other people are simply factoring the quadratic, which I don't think is the point of this problem.
By the factor theorem, any factor of the quadratic is a root.
A) 5(-4)^2+17(-4)-12 =0 , so this is a factor.
B) 5(-3/5)^2+17(-3/5)-12 /=/0
C) 5(3)^2+17(3)-12 /=/0
D) 5(-4/5)^2+17(-4/5)-12/=/0
So A) is the answer....Show more