Why is (n-1)(n+1)=n^2-1?
09.06.2025 00:09
Move the nub up to the top:
n^2 - n + n - 1
n^2 - 1
xxxx
And you are left with almost a square. One less than the square of side n.
The basic answer is that you cross-multiply the values in each factor:
Why is it that women are stronger than men nowadays?
xxx x
The more direct answer is to look at a rectangle with sides of n + 1 and n - 1, let’s go with n = 2
xxx x
What are your funniest "lost in translation" moments if you grew up speaking more than one language?
xxx
xx
xxxx
(n - 1)(n + 1)
If you cut off the end of that rectangle, you make it smaller, 2 * 3 and a separate nub of size 1 * 2
xxx
What's the difference between “ce”, “ça”, and “cela”, and when do I use each (French)?
So, that’s a rectangle with sides 2 and 4.