Question

I forgot how to factorise this! :(
3x^2 +2xy - 8y^2 - 8x +14y-3

Answer 1

Is this your equation? \[3x^2 +2xy - 8y^2 - 8x +14y-3\]

Answer 2

yes

Answer 3

Sorry, I was trying to get my question answered.. Anyways! What do we know? We know that the following can be factored out:
\[x^2\]\[8y^2\]\[14\]
I left out 3 and why because they can only be only be factored out by 1.

Answer 4

Not "why". I meant "y"

Answer 5

umm ok...

Answer 6

Am I not making any sense? damn

Answer 7

for some reason i cant factorise this question :/
i dont see taking out these common factors to be any help...

Answer 8

i know its possible to factorise this but i ahve no idea how
http://www.wolframalpha.com/input/?i=factorize+3x%5E2+%2B2xy+-+8y%5E2+-+8x+%2B14y-3

Answer 9

It will! Promise.

Answer 10

umm, what method of factorising is this?

Answer 11

REVERSE FOIL
Starting with 3x^2 and 8y^2, what can they be factored into?

Answer 12

3 and 1, x and x
2 and 4, y and y

Answer 13

sorry, but i dont understand what your talking about :/

Answer 14

\[3x \times x = 3x^2\]\[2y \times 4y = 8y^2\] Is that not correct?

Answer 15

yes thats correct

Answer 16

But its a negative so \[-4y \times 2y = -8y^2\]

Answer 17

ok

Answer 18

But really from that link you posted, you can take out \[(x+2y-3)\]
From the this you can take out x
\[3x^2 + 2xy - 8x\]
From this you can factor out 2y \[2xy - 8y^2 +14y\]
And lastly -3\[-3\]

Answer 19

...."you can factor out"....

Answer 20

I guess you can I tried to find the greatest common factor in each, instead of reverse foil. Reverse FOIL is mostly for trinomials..

Answer 21

mhm i tried that. Btw i never done reverse foil before so is there any other way?

Answer 22

is it possible if you find the greatest common factor?

Answer 23

Yes. I just showed you...

Also some methods are:
- Number of Terms
- Factor Out the GCF First
- Reversing FOIL
- Guess and Check

Answer 24

Its possible because that is what I did. For your x, you can factor out x ONLY because 3 is not a factor of 8. Also the lowest variable is x in all three.
\[3x^2+2xy−8x\]