can you factor this?

Question

4y^2 + 9y - 28


can you tell me how you did it plz

Answer 1

Here's how you do it. You know that the answer is something like

(ay + b)(cy + d)

So a*c has to equal 4 and b*d has to equal -28. So find all the factors of 4... 1, 2, and 4. The y coefficients must be 1 and 4 or 2 and 2. Next find all the factors of 28. They are 1, 2, 4, 7, 14 and 28. You also know that one of those has to be negative. Now you need to try these out until you get the middle term right. In this case, if you play around with it you will find that 4*4 - 1*7 = 9. So the answer is (4y-7)(1y+4)

Answer 2

4y^2 + 9y - 28

(4y - 7)(y + 4)

you need to find two terms that combine to equal 4y^2; this could be 4y and y; or 2y and 2y.

now look at the third term: you need to find two numbers which when multiplied equal minus 28. That could be 28 and 1, 14 an 2 or 7 and 4. One number will be negative.

now you want to find out which combination of these numbers will give you a +9y. You do this by multiplying the outer two numbers and the inner two numbers.The negative sign in front of the third term tells you that one of the signs of the second terms is negative; the positive sign in front of 9y tells you that the larger of the two products must be a positive value and the smaller one will be negative.

4y^2 = 4y * y
-28 = -7 * 4
9y = [4y * 4 = 16y; y * -7 = -7y; 16y - 7y = 9y]
(4y -7)(y+4)

I hope this helps. Email me if you are still confused or want to understand better.

Answer 3

Yes I can:

(4Y - 7) (Y + 4)

Answer 4

yes

(4y-7)(y+4)

hope this helps!

~mathwhiz~

Answer 5

(y + 4)(4y - 7)

Answer 6

yes