Why is (n-1)(n+1)=n^2-1?
Last Updated: 23.06.2025 00:33

Move the nub up to the top:
xxx x
xxxx
And you are left with almost a square. One less than the square of side n.
n^2 - 1
xxx
We Asked 3 Chefs the Secret to the Best Potato Salad—They All Said the Same Thing - EatingWell
The basic answer is that you cross-multiply the values in each factor:
n^2 - n + 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
Why are Trump's and Khan's experiences with authorities in the US and Pakistan similar?
xxx
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
South Florida-based Silver Airways shuts down, stranding travelers - Sun Sentinel
(n - 1)(n + 1)
So, that’s a rectangle with sides 2 and 4.
xxxx
xx