Factoring EMcAninch

Factoring Equations
FX-14
A)
x^2-49
x^2-49=(x)^2-(7)^2
x^2-(7)^2=(x+7)(x-7)
so
x^2-49=(x+7)(x-7)
B)
4x^2-1
4x^2-1=(2x)^2-(1)^2
(2x)^2-(1)^2=(2x+1)(2x-1)
so
4x^2-1 = (2x+1)(2x-1)
C)
x^2y^2-81z^2
x^2y^2-81z^2=(xy)^2-(9z)^2
(xy)^2-(9z)^2=(xy+9z)(xy-9z)
so
x^2y^2-81z^2=(xy-9z)(xy-9z)
D)
2x^3-8x
2x(x^2-4)
2x(x^2-4)=2x((x)^2-(2)^2)
2x((x)^2-(2)^2)=2x(x+2)(x-2)
so
2x^3-8x=2x(x+2)(x-2)