`#Sad`
`12)`
`a)`
`x^3-8`
`= x^3-2^3`
`= (x-2)(x^2+2x+2^2)`
`= (x-2)(x^2+2x+4)`
`c)`
`8x^3+12x^2+6x+1`
`= (2x)^3+3. (2x)^2. 1+3. 2x. 1+1^3`
`= (2x+1)^3`
`d)`
`x^3-6x^2y+12xy^2-8y^3`
`= x^3-3. x^2. 2y+3. x. (2y)^2-(2y)^3`
`= (x-2y)^3`
`13)`
`4x^2-4x+1`
`= (2x)^2-2. 2x. 1+1^2`
`= (2x-1)^2`
