`g)G=-x(-x-3)-(x+5).(-x)-2x^2`
`=x^2+3x+x^2+5x-2x^2`
`=8x`
`h)H=(-5x-1).x+(-x-3)(2-5x)`
`=-5x^2-x+(x+3)(5x-2)`
`=-5x^2-x+5x^2+13x-6`
`=12x-6`
`i)I=(y-3)(y+3)(y^2+9)-(y^2+5)(y^2-5)`
`=(y^2-9)(y^2+9)-(y^2+5)(y^2-5)`
`=y^4-81-y^4+25=-56`
`k)K=(2x+1)^2-2(2x+1)(2x+5)+(2x+5)^2`
`=(2x+1-2x-5)^2=16`
`m)M=(x-2)^2.x-(x-3)(x^2+3x+27)-10`
`=x^3-4x^2+4x-(x^3+18x-81)-10`
`=-4x^2-14x+71`
`n)N=(x-1)(x^2+x+1)-(x+1)(x^2-x+1)`
`=x^3-1-(x^3+1)=-2`
