Math Is Fun Forum

soha

Real Member

Registered: 2006-07-07

Posts: 2,530

using identity:-

Factorise  using  a²-b² = (a+b)(a-b)
       
         45(2x-3y)²-20(3x-2y)²

Last edited by soha (2008-04-13 23:58:36)

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"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!"
- David O. McKay

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: using identity:-

5[9(2x-3y)²-4(3x-2y)²]

5[(3(2x-3y))² - (2(3x-2y)²]

5[(6x-9y)² - (6x-4y)²]

The bit inside the square brackets is now in a²-b² form, so using the equation you're given can turn this into something much simpler, which you then tidy up.

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Why did the vector cross the road?
It wanted to be normal.

soha

Real Member

Registered: 2006-07-07

Posts: 2,530

Re: using identity:-

can u simplify it using the equation also please

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"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!"
- David O. McKay

SvenBee

Member

Registered: 2008-03-08

Posts: 106

Re: using identity:-

Are you sure that's right mathsyperson?  Because if it is then b= -9y and -4y. Maybe I'm just looking to shallow though... Hmm.

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e...the red-headed stepchild of math.

soha

Real Member

Registered: 2006-07-07

Posts: 2,530

Re: using identity:-

Are you sure that's right mathsyperson?  Because if it is then b= -9y and -4y. Maybe I'm just looking to shallow though... Hmm.

this was the problem for me ....

i solved it till there but then b became a problem .........

if anyone could help in this faster , it would be very very very helpful...

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"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!"
- David O. McKay

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: using identity:-

Are you sure that's right mathsyperson?  Because if it is then b= -9y and -4y. Maybe I'm just looking to shallow though... Hmm.

There aren't two sets of a and b.
It's just a = 6x-9y; b = 6x-4y.

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Why did the vector cross the road?
It wanted to be normal.

soha

Real Member

Registered: 2006-07-07

Posts: 2,530

Re: using identity:-

i thought a=6x and b= 9y or 4y.....................

i will try the way u told now ............

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"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!"
- David O. McKay