Question

i thought i understood how to do this after y'all explained, but wat??

simplify completely

Answer 1

ok, you're going to start the same exact way, ok? factor out the 2 and then ignore it until then end. by factoing out the 2, you are left with x^2 + 8x +15 on the top

Answer 2

mhmm, i did that, but the bottom?!

Answer 3

2(x + 3)(x + 5)/ ??

Answer 4

now, whenever I factor something, what i do is figure out all the multiples of c (which is 15 in this case). All possible multiples are (1,15), (3,5) in this case

Answer 5

now, one of those sets of numbers, when added or subtracted, ahs to equal 8. in this case, it is (3,5)

Answer 6

therefore, the top goes out to 2*(x+5)*(x+3) as you said :)

Answer 7

next, we do the bottom

Answer 8

the bottom's got me really confused :c

Answer 9

so now, we have a 5 before the x. All the factors of 5 are (1,5). All the factors of 6 are (1,6) and (2,3). so by multiplying (1,5) by one of those 2, we need get to 13, does that make sense?

Answer 10

because it's a negative 6, we're going to have one positive and one negative

Answer 11

WAIT we multiply the 5 and -6 right?? then find factors of -30 that add up to 13?

Answer 12

that gives us (1,5) multiplied by (-2,3) since we want the end result to be the value of b, which is 13

Answer 13

1*-2 gives you -2, and 3*5 gives you 15, and then 15+(-2) = 13

Answer 14

let me draw it out for you

Answer 15

You know, you could just factor it with the quadratic equation.

Answer 16

so now the (x+3) will cancel on the top and the bottom, and our answer will be the third choice :)

Answer 17

oh yea, @wio that would have been easier to explain...whoops. you can do that honor, lol

Answer 18

whoops, I meant quadratic formula.

Answer 19

In higher level math, ain't nobody got time to factor. They use the formula.

Answer 20

lol, in higher level math, factoring in your head takes but a second compared to writing out the formula...trust me, im'ma math major at an IT school, lol

Answer 21

you don't write out any formula, you can do the quadratic formula in your head.

Answer 22

Guess and check factoring doesn't work a lot of the time and often can lead to mistake.

Answer 23

meh, once you've seen it enough @wio , it becomes simple enough :)

Answer 24

I've seen about 1000 of them, and trust me quadratic formula is much faster if you master it.

Answer 25

If you say so mate, lol