`a)2x^2+3(x-1)(x+1)-5x(x+1)`
`=2x^2+3(x^2-1)-5x^2-5x`
`=2x^2+3x^2-3-5x^2-5x`
`=(2x^2+3x^2-5x^2)-3-5x`
`=-3-5x`
`b)(8-5x)(x+2)+4(x-2)(x+1)+2(x-2)(x+2)+10`
`=8x+16-5x^2-10x+4(x^2+x-2x-2)+2(x^2-2^2)+10`
`=8x+16-5x^2-10x+4x^2+4x-8x-8+2x^2-8+10`
`=(8x-10x+4x-8x)+(16-8-8+10)+(-5x^2+4x^2+2x^2)`
`=-6x+10+x^2`
`=x^2-6x+10`