(5x^4-10x^3y+25x^2y^2)除以(-5x^2)
=5x^4/(-5x^2)-10x^3y/(-5x^2)+25x^2y^2/(-5x^2)
=-5x^4/5x^2+10x^3y/5x^2-25x^2y^2/5x^2
=-x^2+2xy-5y^210x^3y/5x^2和-25x^2y^2/5x^2为什么等于2xy和-5y^2？10x^3y/5x^2=10/5 x^(3-2)y=2xy -25x^2y^2/5x^2=-25/5 x^(2-2)y^2=-5x^0y^2=-5y^2