1.NounThe identity
x
2
−
y
2
=
(
x
+
y
)
(
x
−
y
)
{\displaystyle x^{2}-y^{2}=(x+y)(x-y)\,}
that holds for all real numbers.
"The fraction
x
−
8
x
2
−
64
{\displaystyle {\frac {x-8}{x^{2}-64}}}
can be simplified to
1
x
+
8
{\displaystyle {\frac {1}{x+8}}}
using the difference of two squares."