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Double Bracket help

Hi All,

ok so i have (x+6)(x-6) and i use the foil method. i am ok doing this but then when i tidy up my expression at the end its going wrong somehow.

F x squared
O -6x
I +6x
L -36

x2-6x+6x-36

heres where i falter. how would you simplify this and could you please explain? Thanks.
Reply 1
Avatar for Nitrogen
Nitrogen
16
6x-6x=0
So you have(x^2)-36=0

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Reply 2
Avatar for zNutty
zNutty
1
Original post by mar090888
Hi All,

ok so i have (x+6)(x-6) and i use the foil method. i am ok doing this but then when i tidy up my expression at the end its going wrong somehow.

F x squared
O -6x
I +6x
L -36

x2-6x+6x-36

heres where i falter. how would you simplify this and could you please explain? Thanks.


Where the two numbers in the brackets are the same, but ones a negative and ones a positive, the x term cancels out (the OI terms). This is called the difference of two squares.
For example: (x-1)(x+1)

F x squared
O -x
I +x
L -1

which equals x squared -1.
Original post by mar090888
Hi All,

ok so i have (x+6)(x-6) and i use the foil method. i am ok doing this but then when i tidy up my expression at the end its going wrong somehow.

F x squared
O -6x
I +6x
L -36

x2-6x+6x-36

heres where i falter. how would you simplify this and could you please explain? Thanks.


(X+a)(x-a) generally simplifies to x^2-a^2, this is known as difference of two squares factorization.

Posted from TSR Mobile
Reply 4
Avatar for mar090888
mar090888
OP
Thanks for the fast replys people much appreciated.

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