(7-2x+x^2)-(5+3x-2x^2)=7-2x+x^2-5-3x+2x^2=2-5x+3x^2-(x^3+2x^2-1)+(x^3-2x^2+x-2)=-x^3-2x^2+1+x^3-2x^2+x-2=-4x^2+x-1(2ax-3by-5)-2(ax-2)+(-2by+1)=2ax-3by-5-2ax+4-2by+1=-5by【数学辅导团】为您解答,如果本题...