8.00自己前要8.00前要

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8.00自己前要8.00前要
8.00自己前要
8.00前要

8.00自己前要8.00前要
1.填空:
(1)xy (2)a-3 (3)m+n
2.C
3.计算:
(1)(a²-64)/(a-8);
=(a+8)(a-8)/(a-8)
=a+8
(2) (3x³y²+6x²y³)/(x+2y);
=3x²y²(x+2y)/(x+2y)
=3x²y²
(3)(-9m²+4n²)/(3m+2n).
=(2n+3m)(2n-3m)/(3m+2n)
=2n-3m
4.接下列方程:
(1)x²+2x=0;
x(x+2)=0
则x=0,或x+2=o
∴原方程的根是x1=0,x2=-2
(2)9x²-4=0
(3x+2)(3x-2)=0
则3x+2=0,或3x-2=0
∴原方程的根是x1=2/3,x2=-2/3
5.计算:
(1)(4a²-20ab+25b²)/(5b-2a)
=(2a-5b)²/(5b-2a)
=-2a+5b
(2)(1-16a四次方)/(4a²+1)/(2a+1)
=(1+4a²)(1-4a²)/(4a²+1)/(2a+z)
=(1+2a)(1-2a)/(2a+1)
=1-2a
6.解方程:
(1)-1/2x²+2x=0
1/2x(-x+4)=0
则1/2x=0,或-x+4=0
∴原方程的根是x1=0,x2=4
(2)(3a-4)²=25
[(3a-4)+5][(3a-4)-5]=0
(3a+1)(3a-9)=0
则3a+1=0,或3a-9=0
∴原方程的根是a1=-1/3,a2=3

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