## AonZ Group Title I forgot how to factorise this! :( 3x^2 +2xy - 8y^2 - 8x +14y-3 one year ago one year ago

1. ilfy214 Group Title

Is this your equation? $3x^2 +2xy - 8y^2 - 8x +14y-3$

2. AonZ Group Title

yes

3. ilfy214 Group Title

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.

4. ilfy214 Group Title

Not "why". I meant "y"

5. AonZ Group Title

umm ok...

6. ilfy214 Group Title

Am I not making any sense? damn

7. AonZ Group Title

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

8. AonZ Group Title

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

9. ilfy214 Group Title

It will! Promise.

10. AonZ Group Title

umm, what method of factorising is this?

11. ilfy214 Group Title

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

12. ilfy214 Group Title

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

13. AonZ Group Title

14. ilfy214 Group Title

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

15. AonZ Group Title

yes thats correct

16. ilfy214 Group Title

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

17. AonZ Group Title

ok

18. ilfy214 Group Title

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$-3$

19. ilfy214 Group Title

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

20. ilfy214 Group Title

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

21. AonZ Group Title

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

22. AonZ Group Title

is it possible if you find the greatest common factor?

23. ilfy214 Group Title

Yes. I just showed you... Also some methods are: - Number of Terms - Factor Out the GCF First - Reversing FOIL - Guess and Check

24. ilfy214 Group Title

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. $3x^2+2xy−8x$

25. AonZ Group Title

|dw:1376184367770:dw|

26. ilfy214 Group Title

you forgot to completely factor out $( 8x^2 - 14y)$

27. AonZ Group Title

|dw:1376184611607:dw|

28. ilfy214 Group Title

Also, this equation is an alternate form of your polynomial, not your polynomial factored out... Besides did you mean to write this instead?$x (3 x+2 y-8)+(14-8 y) y-3$

29. AonZ Group Title

mhm yea

30. ilfy214 Group Title

Its okay :)

31. ilfy214 Group Title

Lets try this again! Take out your GCF from your polynomial.... $3x^2 +2xy - 8y^2 - 8x +14y - 3$

32. AonZ Group Title

not sure how...

33. ilfy214 Group Title

X, Y and your constant are separate cases. Like what I wrote if you scroll up.

34. ilfy214 Group Title

Let me try again! Here is your GCF, right? $(x+2y − 3)$ When it comes to your x variables, only x can be factored out since 3 is not a factor of 8 even thought 2 is. Also you can't factor out x^2 because each monomial does not x^2. They all have at least one. $3x^2 + 2xy − 8x$ Also these monomials are the only ones with an "x"

35. AonZ Group Title

still dont get how you got ur GCF...

36. ilfy214 Group Title

When it come to your y variables, you can factor out 2y because 2 is the greatest common factor. $2xy−8y^2+14y$ And lastly for -3. It is the only constant. So when factoring, all you will use is (1) (-3) $−3$

37. ilfy214 Group Title

Do you know what the term GCF is? GREATEST COMMON FACTOR

38. AonZ Group Title

yea... but how did you get it...

39. ilfy214 Group Title

I thought I just showed you and explained it to you..

40. ilfy214 Group Title

EXAMPLE: What are the factors and GCF for these numbers? 2 - 1, 2 3 - 1, 3 12 - 1, 2, 3, 4, 6, 12 The GCF for these is 1.