Why is (n-1)(n+1)=n^2-1?
10.06.2025 01:30
xxx
The basic answer is that you cross-multiply the values in each factor:
So, that’s a rectangle with sides 2 and 4.
Southwest Floats First Class, Lounges, Long Haul Flying: Good Strategy? - One Mile at a Time
If you cut off the end of that rectangle, you make it smaller, 2 * 3 and a separate nub of size 1 * 2
Move the nub up to the top:
n^2 - n + n - 1
Brave x Junction demo now available - Gematsu
xxx x
xxx
xxx x
Astronomers Have Detected a Galaxy Millions of Years Older Than Any Previously Observed - WIRED
n^2 - 1
xx
The more direct answer is to look at a rectangle with sides of n + 1 and n - 1, let’s go with n = 2
Asteroid 2024 YR4 Could Strike the Moon: NASA’s Webb Telescope Warns - The Daily Galaxy
xxxx
And you are left with almost a square. One less than the square of side n.
(n - 1)(n + 1)
xxxx