题目内容
(1)
(-4x+8)-3(4-5x)
(2)5(2x-3)-4(3-2x)
(3)现规定
=a-b+c-d,试计算:
,其中x=-2,y=1.
1 |
4 |
(2)5(2x-3)-4(3-2x)
(3)现规定
|
|
(1)原式=-x+2-12+15x=14x-10;
(2)原式=10x-15-12+8x=18x-30;
(3)原式=(xy-3x2)(-5+xy)-(-2x2-3)(-2xy-x2)=-5xy+x2y2+15x2-3x3y-4x3y+2x4+6xy-3x2=xy+x2y2+15x2-7x3y+2x4,
当x=-2,y=1时,原式=-2+4+60+56+32=150.
(2)原式=10x-15-12+8x=18x-30;
(3)原式=(xy-3x2)(-5+xy)-(-2x2-3)(-2xy-x2)=-5xy+x2y2+15x2-3x3y-4x3y+2x4+6xy-3x2=xy+x2y2+15x2-7x3y+2x4,
当x=-2,y=1时,原式=-2+4+60+56+32=150.
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