-4(qp+pr)+(4qp+pr) 先拆开
=-4qp-4pr+4qp+pr 合并同类项
=(-4+4)qp+(-4+1)pr
=-3pr
-5(x-2y+1)-(1-3x+4y)先拆开
=-5x+10y-5-1+3x-4y 合并同类项
=(-5+3)x+(10-4)y-5-1
=-2x+6y-6
-3(x-(1/2)y^2)+(-x+(1/2)y^2) 这里前面括号里的内容和后面括号里的内容是相反数
=(-3-1)(x-(1/2)y^2)
=-4(x-(1/2)y^2) 括号拆开
=-4x+2y²