20.37 срочно, пожалуйста!!!

2) x³-3x²+2=x³-x²-2x²+2=x²(x-1)-2(x²-1)=x²(x-1)-2(x-1)(x+1)=(x-1)(x²-2(x+1))=
=(x-1)(x²-2x-2);
4) a³-3ab²-2b³=a³-ab²-2ab²-2b³=a(a²-b²)-2b²(a+b)=a(a-b)(a+b)-2b²(a+b)=
=(a+b)(a(a-b)-2b²)=(a+b)(a²-ab-2b²);
$5) x^{8}+ x^{7}+1= \\ = x^{8}+x^{7}+x^{6}-x^{6}+x^{5}-x^{5}+x^{4}-x^{4}+ x^{3}- x^{3} + \\ +x^{2} - x^{2} +x-x+1= \\ =( x^{8}+ x^{7}+ x^{6})-( x^{6}+ x^{5}+ x^{4})+( x^{5}+ x^{4}+ x^{3})- \\ -( x^{3}+ x^{2} +x)+( x^{2} +x+1)= \\ x^{6}( x^{2} +x+1)- x^{4}( x^{2} +x+1)+ x^{3}( x^{2} +x+1)-x( x^{2} +x+1)+ \\ +( x^{2} +x+1)=( x^{2} +x+1)( x^{6}- x^{4}+ x^{3}-x+1).$