优质解答
(1)原式=5x2-3x+4x-6+4x2=9x2+x-6;
(2)原式=5x2y-3xy2-7x2y+2xy2=-2x2y-xy2,
当x=2,y=-1时,原式=8-2=6;
(3)原式=2x5-3x2y-2xy2-x5+2xy2-y5-x5+3x2y-y5=-2y5,
当x=0.5,y=-1时,原式=2.
结果与x取值无关,故甲同学把x=0.5错抄成x=-0.5,但他计算的结果是正确的.
(1)原式=5x2-3x+4x-6+4x2=9x2+x-6;
(2)原式=5x2y-3xy2-7x2y+2xy2=-2x2y-xy2,
当x=2,y=-1时,原式=8-2=6;
(3)原式=2x5-3x2y-2xy2-x5+2xy2-y5-x5+3x2y-y5=-2y5,
当x=0.5,y=-1时,原式=2.
结果与x取值无关,故甲同学把x=0.5错抄成x=-0.5,但他计算的结果是正确的.