I know it's easy to all you people, but my first question is, is this right:(adsbygoogle = window.adsbygoogle || []).push({});

Difference between ( X) x (X+21) and (X+1) x (X+20)=20

=(x²+x+20x+20)-(x²+21x)

=(x²+21x+20)-(x²+21x)

=(21x+20)-21x

=20

I think it is, that's one point

Point 2

I just can't find an expression which connects N(or Size) with Difference

N Size Difference

1 2x2 40

2 3x3 160

3 4x4 240

4 5x5 640

Thanks In Advance

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# Homework Help: Algebra and Finding a fomula

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