# Do I use FOIL?

• June 17th 2008, 03:23 AM
risteek
Do I use FOIL?
I have a bunch of questons but I don't know if I use FOIL in them and how to sepearte them for BEDMASS and stuff. :/

Here is an example of one:

(X+5)(X+4)+4(2X-2)²-(3X-4)(3X+4)

Please if you can help me with this one then I am sure I can manage through the rest. Thanks guys!
• June 17th 2008, 03:54 AM
janvdl
Quote:

Originally Posted by risteek
I have a bunch of questons but I don't know if I use FOIL in them and how to sepearte them for BEDMASS and stuff. :/

Here is an example of one:

(X+5)(X+4)+4(2X-2)²-(3X-4)(3X+4)

Please if you can help me with this one then I am sure I can manage through the rest. Thanks guys!

I do believe it is called BODMAS actually.

$(x+5)(x+4) \ \ + \ \ 4(2x-2)^2 \ \ - \ \ (3x-4)(3x+4)
$

$(x^2 + 9x + 20) \ \ + \ \ 4(2x-2)(2x-2) \ \ - \ \ (9x^2 - 16)
$

$(x^2 + 9x + 20) \ \ + \ \ 4(4x^2 - 8x + 4) \ \ - \ \ (9x^2 - 16)
$

$(x^2 + 9x + 20) \ \ + \ \ (16x^2 - 32x + 16) \ \ - \ \ (9x^2 - 16)
$

And i think you can solve from here.
• June 17th 2008, 05:06 AM
colby2152
Quote:

Originally Posted by janvdl
I do believe it is called BODMAS actually.

$(x+5)(x+4) \ \ + \ \ 4(2x-2)^2 \ \ - \ \ (3x-4)(3x+4)
$

$(x^2 + 9x + 20) \ \ + \ \ 4(2x-2)(2x-2) \ \ - \ \ (9x^2 - 16)
$

$(x^2 + 9x + 20) \ \ + \ \ 4(4x^2 - 8x + 4) \ \ - \ \ (9x^2 - 16)
$

$(x^2 + 9x + 20) \ \ + \ \ (16x^2 - 32x + 16) \ \ - \ \ (9x^2 - 16)
$

And i think you can solve from here.

Well, in the states, students learn expansion of two terms by the FOIL acronym. First, outside, inside, last.

F, stands for first, or the 1st variables/numbers of $(x+5)(x+4)$ which are x and x

$x*x + = x^2$

O, stands for outside, or the two variables/numbers on the outside, or x and 4.

$x*4 = 4x$

I, stands for inside, or the insides... 5 and x

$5*x = 5x$

L, stands for last, or the last (2nd) variables/numbers of the product of terms

$5*4 = 20$

Sum them up for the result: $x^2 + 4x + 5x + 20 = x^2 + 9x + 20$
• June 17th 2008, 11:20 AM
risteek
Canada and the U.S use FOIL I suppose seeing as I'm Canadian :p

Thank you guys so much =D I love this forum!
• June 17th 2008, 11:35 AM
janvdl
Quote:

Originally Posted by risteek
Canada and the U.S use FOIL I suppose seeing as I'm Canadian :p

Thank you guys so much =D I love this forum!

BODMAS -> Brackets ; Of ; Div/Multi ; Add/Sub
• June 17th 2008, 11:37 AM
risteek
I never heard of it that way. I will have to show my math teacher she loves different math things. :p
• June 17th 2008, 11:38 AM
Mathstud28
Parentheses
Exponents
Multiply
Divide