Why is (n-1)(n+1)=n^2-1?
13.06.2025 08:10

xxxx
The basic answer is that you cross-multiply the values in each factor:
xxx
Move the nub up to the top:
n^2 - n + n - 1
So, that’s a rectangle with sides 2 and 4.
Webb telescope images frigid exoplanet in strange orbit - Phys.org
(n - 1)(n + 1)
xxx x
If you cut off the end of that rectangle, you make it smaller, 2 * 3 and a separate nub of size 1 * 2
Is the Chinese economy currently collapsing? If not, what could potentially cause it to collapse?
xxx x
xxxx
n^2 - 1
xx
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
xxx