计算: (1) (3x2+4x-1)-3(x2+3x); (2)-(x2y+3xy-4)+3(x2y-xy+2).
问题描述:
计算:
(1) (3x2+4x-1)-3(x2+3x);
(2)-(x2y+3xy-4)+3(x2y-xy+2).
答
(1)原式=3x2+4x-1-3x2-9x=-5x-1;
(2)原式=-x2y-3xy+4+3x2y-3xy+6=2x2y-6xy+10.