1.已知1/a-1/b=5,则(2a+3ab-2b)/(a-2b-b)的值是2.若(1-3x)/(x^2-1)=A/(x+1)+B/(x-1),则A= B=3.已知a,b为实数,且ab=1,设M=a/(a+1)+b/(b+1),N=1/(a+1)+1/(b+1)则MN的大小关系
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![1.已知1/a-1/b=5,则(2a+3ab-2b)/(a-2b-b)的值是2.若(1-3x)/(x^2-1)=A/(x+1)+B/(x-1),则A= B=3.已知a,b为实数,且ab=1,设M=a/(a+1)+b/(b+1),N=1/(a+1)+1/(b+1)则MN的大小关系](/uploads/image/z/5334403-67-3.jpg?t=1.%E5%B7%B2%E7%9F%A51%2Fa-1%2Fb%3D5%2C%E5%88%99%282a%2B3ab-2b%29%2F%28a-2b-b%29%E7%9A%84%E5%80%BC%E6%98%AF2.%E8%8B%A5%281-3x%29%2F%28x%5E2-1%29%3DA%2F%28x%2B1%29%2BB%2F%28x-1%29%2C%E5%88%99A%3D+B%3D3.%E5%B7%B2%E7%9F%A5a%2Cb%E4%B8%BA%E5%AE%9E%E6%95%B0%2C%E4%B8%94ab%3D1%2C%E8%AE%BEM%3Da%2F%28a%2B1%29%2Bb%2F%28b%2B1%29%2CN%3D1%2F%28a%2B1%29%2B1%2F%28b%2B1%29%E5%88%99MN%E7%9A%84%E5%A4%A7%E5%B0%8F%E5%85%B3%E7%B3%BB)
1.已知1/a-1/b=5,则(2a+3ab-2b)/(a-2b-b)的值是2.若(1-3x)/(x^2-1)=A/(x+1)+B/(x-1),则A= B=3.已知a,b为实数,且ab=1,设M=a/(a+1)+b/(b+1),N=1/(a+1)+1/(b+1)则MN的大小关系
1.已知1/a-1/b=5,则(2a+3ab-2b)/(a-2b-b)的值是
2.若(1-3x)/(x^2-1)=A/(x+1)+B/(x-1),则A= B=
3.已知a,b为实数,且ab=1,设M=a/(a+1)+b/(b+1),N=1/(a+1)+1/(b+1)则MN的大小关系
1.已知1/a-1/b=5,则(2a+3ab-2b)/(a-2b-b)的值是2.若(1-3x)/(x^2-1)=A/(x+1)+B/(x-1),则A= B=3.已知a,b为实数,且ab=1,设M=a/(a+1)+b/(b+1),N=1/(a+1)+1/(b+1)则MN的大小关系
1) 1/a-1/b=(b-a)/(ab)=5, a-b=-5ab
(2a+3ab-2b)/(a-2ab-b)=(3ab-2*5ab)/(-5ab-2ab)=1
2) A/(x+1)+B/(x-1)=[A(x-1)+B(x+1)]/(x^2-1)
=[(A+B)x+B-A]/(x^2-1) = (1-3x)/(x^2-1)
所以:A+B=-3, B-A=1,
A=-2, B=-1
3) M=a/(a+1)+b/(b+1)= 1-1/(a+1)+1-1/(b+1)=2-[1/(a+1)+1/(b+1)]
M-N=2-2[1/(a+1)+1/(b+1)]=2-2(a+1+b+1)/[(a+1)(b+1)]
=2-2(a+b+2)/(ab+a+b+1)
=2-2(a+b+2)/(a+b+2)
=2-2=0
所以M=N
1、原式=2+7ab/(a-2ab-b)
=2+7/(1/b-2-1/a)
=1
2、右边=(Ax+Bx-A+B)/(x^2-1)
由系数对应相等
A+B=-3
B-A=1
得出A=-2,B=-1
3、对MN通分知
M=N