化简:(1)
;
(2)3x 2﹣[7x﹣(4x﹣3)﹣2x 2]
(3)(2xy﹣y)﹣(﹣y+yx)
(4)5(a 2b﹣3a
)﹣2(a 2b﹣7ab 2)
(1)原式=(
﹣4)mn=﹣
;
(2)原式=3x 2﹣7x+4x﹣3+2x 2
=(3+2)x 2+(﹣7+4)x﹣3
=5x 2﹣3x﹣3;
(3)(2xy﹣y)﹣(﹣y+yx)
=2xy﹣y+﹣y﹣yx
=xy;
(4)5(a 2b﹣3ab 2)﹣2(a 2b﹣7ab 2)
=5a 2b﹣15ab 2﹣2a 2b+14ab 2
=(5﹣2)a 2b﹣(15﹣14)ab 2
=3
﹣a
.