[tex]2(3x+1)+(1-2x)=6x+2+1-2x=4x+3[/tex]
[tex]x*x+x+x:x= x^{2} +x+1[/tex]
[tex] x^{8} : x^{7} + x^{6} : x^{5}-x ^{4} : x^{3} + x^{2} :x=x^{8-7} +x^{6-5}-x^{4-3}+x^{2-1}=[/tex][tex]x+x-x+x=2x[/tex]
[tex](x-2)(x+2)= x^{2} +2x-2x-4= x^{2} -4[/tex]
[tex](x+4)(x-3)-x+12= x^{2} -3x+4x-12-x+12= x^{2} [/tex]