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Why is (n-1)(n+1)=n^2-1?

10.06.2025 01:37

Why is (n-1)(n+1)=n^2-1?

The basic answer is that you cross-multiply the values in each factor:

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If you cut off the end of that rectangle, you make it smaller, 2 * 3 and a separate nub of size 1 * 2

Are today’s baseball pitchers faster than a few years ago, or is it that radar guns have improved and get the pitch speed as it is released rather than as it reaches the plate?

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Move the nub up to the top:

What would be the lowest score with 9 strikes and no gutter balls?

n^2 - n + n - 1

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(n - 1)(n + 1)

China tightens ‘whole-chain’ control on critical minerals amid US pressures - South China Morning Post

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Dejected Joshua Kimmich reacts to Germany’s Nations League defeat - Bavarian Football Works

So, that’s a rectangle with sides 2 and 4.

And you are left with almost a square. One less than the square of side n.

The more direct answer is to look at a rectangle with sides of n + 1 and n - 1, let’s go with n = 2

How can I remove decimals in math?

n^2 - 1