Posted by **Nat** on Saturday, March 15, 2008 at 6:32am.

I have a maths exam tomorrow and am studying with a friend. We are working on a question and are getting two different answers. Could you please show us the right way to do it?

2(4x + 3)(4x - 3) - (4x + 3)squared

p.s i couldn't find a squared symbol so only the last bracket is squared, not the whole equation.

- Maths -
**Reiny**, Saturday, March 15, 2008 at 7:17am
2(4x + 3)(4x - 3) - (4x + 3)squared

we usually write it this way

2(4x + 3)(4x - 3) - (4x + 3)^2

= 2(16x^2 - 9) - (4x + 3)(4x + 3)

= 2(16x^2 - 9) - (16x^2 + 24x + 9)

= 32x^2 - 18 - 16x^2 - 24x - 9

= 16x^2 24x - 27

or you could take out a common factor from

2(4x + 3)(4x - 3) - (4x + 3)^2

= (4x + 3)(2(4x-3) - (4x+3))

= (4x+3)(8x-6-4x-3)

= (4x+3)(4x-9)

= 16x^2 - 36x + 12x - 27

= 16x^2 - 24x - 27

not saying the second way is any easier, just another way to show it

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