1/
`(x^2-1)^3-(x^4+x^2+1)(x^2-1)`
`=(x^2-1)[(x^2-1)^2-x^4-x^2-1]`
`=(x^2-1)[x^4-2x^2+1-x^4-x^2-1]`
`=(x^2-1)(-3x^2)`
`=-3x^4+3x^2`
2/
`C=(x-1)^3-4x(x+1)(x-1)+3(x-1)(x^2+x+1)`
`=(x-1)^3-4x(x^2-1)+3(x^3-1)`
`=(-2-1)^3-4(-2)[(-2)^2-1]+3[(-2)^3-1]`
`=27+24-27`
`=24`
3/
`M=(x+y)^3+2x^2+4xy+2y^2`
`M=(x+y)^3+2(x^2+2xy+y^2)`
`M=(x+y)^3+2(x+y)^2`
`M=7^3+2.7^2`
`M=441`