`M(x)=10x^{5}-8x^{4}+6x^{3}-4x^{2}+2x+1`
`N(x)=-10x^{5}+2x^{4}-4x^{3}+6x^{2}-8x+10`
`M(x)+N(x)=(10x^{5}-8x^{4}+6x^{3}-4x^{2}+2x+1)+(-10x^{5}+2x^{4}-4x^{3}+6x^{2}-8x+10)`
`=10x^{5}-8x^{4}+6x^{3}-4x^{2}+2x+1-10x^{5}+2x^{4}-4x^{3}+6x^{2}-8x+10`
`=(10x^{5}-10x^{5})+(-8x^{4}+2x^{4})+(6x^{3}-4x^{3})+(-4x^{2}+6x^{2})+(2x-8x)+(1+10)`
`=-6x^{4}+2x^{3}+2x^{2}-6x+11`
`N(x)-M(x)=(-10x^{5}+2x^{4}-4x^{3}+6x^{2}-8x+10)-(10x^{5}-8x^{4}+6x^{3}-4x^{2}+2x+1)`
`=-10x^{5}+2x^{4}-4x^{3}+6x^{2}-8x+10-10x^{5}+8x^{4}-6x^{3}+4x^{2}-2x-1`
`=(-10x^{5}-10x^{5})+(2x^{4}+8x^Ơ4})+(-4x^{3}-6x^{3})+(6x^{2}+4x^{2})+(-8x-2x)+(10-1)`
`=-20x^{5}+10x^{4}-10x^{3}+10x^{2}-10x+9`
`M(x)-N(x)=(10x^{5}-8x^{4}+6x^{3}-4x^{2}+2x+1)-(-10x^{5}+2x^{4}-4x^{3}+6x^{2}-8x+10)`
`=10x^{5}-8x^{4}+6x^{3}-4x^{2}+2x+1+10x^{5}-2x^{4}+4x^{3}-6x^{2}+8x-10`
`=(10x^{5}+10x^{5})+(-8x^{4}-2x^{4})+(6x^{3}+4x^{3})+(-4x^{2}-6x^{2})+(2x+8x)+(1-10)`
`=20x^{5}-10x^{4}+10x^{3}-10x^{2}+10x-9`
$\text{Xin hay nhất }$
