Question

How to find the SUM of the solution of the equation:
8x^2+40x=16x

Answer 1

8x^2 + 40x = 16x
(-16x)
8x^2 + 32x = 0
8x(x + 4) = 0
I'll let you take it from here.

Answer 2

Set 8x = 0 and (x +4) = 0 , then the results add together

Answer 3

Correct, since it asks for the sum. You get two results, one from either factor.

Answer 4

Thanks! How did you get 32x?

Answer 5

By subtracting 16x from both sides and then grouping like terms. Like this:
8x^2 +40x = 16x
8x^2 +40x -16x = 16x-16x
8x^2 +32x = 0

Answer 6

So you subtracted 16x-16x, do you also subtract 40x-16x? If so, wouldn't that equal 24x?

Answer 7

Yes. Haha thank you for catching that.

Answer 8

Embarassing.

Answer 9

haha. It's okay!

Answer 10

So after, do you divide each by 8?

Answer 11

Yeah. I get
8x^2 + 24x = 0
and you can take out a factor of 8x

Answer 12

So the answer would be 3?

Answer 13

Kind of almost.

Answer 14

You get a factor of (x+3)
What x makes that factor 0?

Answer 15

you can factor out as 4x(2x+6) then set both to zero and you should end up with x= 0 & x = -3 and add them

Answer 16

So the answer is -3?

Answer 17

yep

Answer 18

That was easy! Thanks you guys!