初二整式除法四道题,速速速速速速速速速1:化简求值:[(3m+4n)²-3m(3m+4n)]÷(-6m),其中m=1,n=32:已知m-2n=3,求[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷1/3m的值3:已知2a-b=5.求[(a²+b²)+2b(a-b)-(a-b)²]÷4b

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初二整式除法四道题,速速速速速速速速速1:化简求值:[(3m+4n)²-3m(3m+4n)]÷(-6m),其中m=1,n=32:已知m-2n=3,求[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷1/3m的值3:已知2a-b=5.求[(a²+b²)+2b(a-b)-(a-b)²]÷4b

初二整式除法四道题,速速速速速速速速速1:化简求值:[(3m+4n)²-3m(3m+4n)]÷(-6m),其中m=1,n=32:已知m-2n=3,求[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷1/3m的值3:已知2a-b=5.求[(a²+b²)+2b(a-b)-(a-b)²]÷4b
初二整式除法四道题,速速速速速速速速速
1:化简求值:[(3m+4n)²-3m(3m+4n)]÷(-6m),其中m=1,n=3
2:已知m-2n=3,求[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷1/3m的值
3:已知2a-b=5.求[(a²+b²)+2b(a-b)-(a-b)²]÷4b的值
4:已知x²+x+1=0,求x³-x²-x+7的值

初二整式除法四道题,速速速速速速速速速1:化简求值:[(3m+4n)²-3m(3m+4n)]÷(-6m),其中m=1,n=32:已知m-2n=3,求[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷1/3m的值3:已知2a-b=5.求[(a²+b²)+2b(a-b)-(a-b)²]÷4b
1:[(3m+4n)²-3m(3m+4n)]÷(-6m)
=[(3m+4n)(3m+4n-3m)]/(-6m)
=(3m+4n)*4n/(-6m)
=(3*1+4*3)*4*3/(-6*1)=-30

2:[(3m+2n)(3m-2n)-(m+2n)(5m-2n)]÷1/3m
=(9m^2-4n^2-5m^2-8mn+4n^2)/(1/3m)
=(4m^2-8mn)/(1/3m)
=4m(m-2n)/(1/3m)
=12(m-2n)
=12*3=36

3:[(a²+b²)+2b(a-b)-(a-b)²]÷4b
=(4ab-2b^2)/4b
=(2a-b)/2=5/2

4:x³-x²-x+7
=x³-1-x²-x+8
.【利用公式x³-1=(x-1)(x²+x+1)】
=(x-1)(x²+x+1)-(x²+x-8) .【思路:将(x²+x-8) 设法写成含有(x²+x+1)的式子】
=(x-1)(x²+x+1)-(x²+x+1)+9
=(x-2)(x²+x+1)+9
=(x-2)*0+9

1.=[(3m+4n)(3m+4n-3m)]/(-6m)
=(3m+4n)*4n/(-6m)
=(3*1+4*3)*4*3/(-6*1)
=-30
2.=(9m^2-4n^2-5m^2-8mn+4n^2)/(1/3m)
=(4m^2-8mn)/(1/3m)
=4m(m-2n)/(1/3m)
=12(m-2n)
=12*3...

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1.=[(3m+4n)(3m+4n-3m)]/(-6m)
=(3m+4n)*4n/(-6m)
=(3*1+4*3)*4*3/(-6*1)
=-30
2.=(9m^2-4n^2-5m^2-8mn+4n^2)/(1/3m)
=(4m^2-8mn)/(1/3m)
=4m(m-2n)/(1/3m)
=12(m-2n)
=12*3=36
3.=(a^2+b^2+2ab-2b^2-a^2+2ab-b^2)/4b
=(4ab-2b^2)/4b
=(2a-b)/2
=5/2

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