12到计算题,1点之前算完.急.1.2x²（x-1/2)×2.5ab×(2a-b+0.2)3.(2a²-2/3a-4/9)×(-9a)4.(x-6)×(x-3)5.(x+1/2)(x-1/3)6.(3x+2)(x+2)7.(4y-1)×(y-5)8.(x-2)(x²+4)9.(x-y)(x²+xy+y²)10.x²(x-1)-x(x²+x-1),其中x=1/2
更新时间： 2024-04-26 15:56:36
1人问答
问题描述：
12到计算题,1点之前算完.急.
1.2x²（x-1/2)×
2.5ab×(2a-b+0.2)
3.(2a²-2/3a-4/9)×(-9a)
4.(x-6)×(x-3)
5.(x+1/2)(x-1/3)
6.(3x+2)(x+2)
7.(4y-1)×(y-5)
8.(x-2)(x²+4)
9.(x-y)(x²+xy+y²)
10.x²(x-1)-x(x²+x-1),其中x=1/2
11.(x-3)(x-3)-6(x²+x-1)
12.(2x+1)²-(x+3)²-(x-1)²+1
陆毅明回答：
1.2x²（x-1/2)×=2x^3-x^2
2.5ab×(2a-b+0.2)=10a^2b-5ab^2+ab
3.(2a²-2/3a-4/9)×(-9a)=-18a^3+6a^2+4a
4.(x-6)×(x-3)=x^2-9x+18
5.(x+1/2)(x-1/3)=x^2+1/6x-1/6
6.(3x+2)(x+2)=3x^2+8x+4
7.(4y-1)×(y-5)=4y^2-21y+5
8.(x-2)(x²+4)=x^3-2x^2+4x-8
9.(x-y)(x²+xy+y²)=x^3-y^3
10.x²(x-1)-x(x²+x-1)=(x^3-x^2)-(x^3+x^2-x)=-2x^2+x
将x=1/2代入可求得结果为0
11.(x-3)(x-3)-6(x²+x-1)=(x^2-9)-(6x^2+6x-6)=-5x^2-6x-3
12.(2x+1)²-(x+3)²-(x-1)²+1=(4x^2+4x+1)-(x^2+6x+9)-(x^2-2x+1)+1=2x^2-8
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