作业帮1、-2(xy-3x²)-2y²-[(4xy+x²)-xy]2、-2(-3ab+2c)+3(-2ab-5c)3、2a²-2[3a-2(-a²+2a-1)-4],其中a=2.4、-2a-{4a-2b-[3a-(2b+1]},其中a=-1,b=2004.
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![1、-2(xy-3x²)-2y²-[(4xy+x²)-xy]2、-2(-3ab+2c)+3(-2ab-5c)3、2a²-2[3a-2(-a²+2a-1)-4],其中a=2.4、-2a-{4a-2b-[3a-(2b+1]},其中a=-1,b=2004.](/uploads/image/z/12442445-53-5.jpg?t=1%E3%80%81-2%28xy-3x%26%23178%3B%29-2y%26%23178%3B-%5B%284xy%2Bx%26%23178%3B%29-xy%5D2%E3%80%81-2%28-3ab%2B2c%29%2B3%28-2ab-5c%293%E3%80%812a%26%23178%3B-2%5B3a-2%28-a%26%23178%3B%2B2a-1%29-4%5D%2C%E5%85%B6%E4%B8%ADa%3D2.4%E3%80%81-2a-%7B4a-2b-%5B3a-%282b%2B1%5D%7D%2C%E5%85%B6%E4%B8%ADa%3D-1%2Cb%3D2004.)
1、-2(xy-3x²)-2y²-[(4xy+x²)-xy]2、-2(-3ab+2c)+3(-2ab-5c)3、2a²-2[3a-2(-a²+2a-1)-4],其中a=2.4、-2a-{4a-2b-[3a-(2b+1]},其中a=-1,b=2004.
1、-2(xy-3x²)-2y²-[(4xy+x²)-xy]
2、-2(-3ab+2c)+3(-2ab-5c)
3、2a²-2[3a-2(-a²+2a-1)-4],其中a=2.
4、-2a-{4a-2b-[3a-(2b+1]},其中a=-1,b=2004.
1、-2(xy-3x²)-2y²-[(4xy+x²)-xy]2、-2(-3ab+2c)+3(-2ab-5c)3、2a²-2[3a-2(-a²+2a-1)-4],其中a=2.4、-2a-{4a-2b-[3a-(2b+1]},其中a=-1,b=2004.
1、-2(xy-3x²)-2y²-[(4xy+x²)-xy]
= -2xy +6x² - 2 y² - 4xy - x² + xy
=5x²-5xy -2y²
2、-2(-3ab+2c)+3(-2ab-5c)
=6ab - 4c -6ab -15c
=- 19c
3、2a²-2[3a-2(-a²+2a-1)-4],其中a=2.
=2a² - 6a -4a² +8a -4 +8
=- 2a² + 2a +4
=0
4、-2a-{4a-2b-[3a-(2b+1]},其中a=-1,b=2004.
=-2a -4a + 2b +3a -2b -1
=- 3a - 1
=2