a: \(4x^2-4x\)
\(=4x\cdot x-4x\cdot1\)
\(=4x\left(x-1\right)\)
b: \(x^2-2xy+y^2-4\)
\(=\left(x-y\right)^2-2^2\)
\(=\left(x-y-2\right)\left(x-y+2\right)\)
`4x^2-4x`
`= 4x(x-1)`
__
`x^2 -2xy +y^2-4`
`= (x^2-2xy+y^2)-2^2`
`=(x-y)^2 -2^2`
`=(x-y-2)(x-y+2)`
a,
\(4x^2-4x\\=4x(x-1)\)
b,
\(x^2-2xy+y^2-4\\=(x^2-2xy+y^2)-4\\=(x-y)^2-2^2\\=(x-y-2)(x-y+2)\)
\(\text{#}Toru\)