若4a-1/(a+2)(a-1)=m/(a+2) + n/(a-1),求m,n的值快点啦,要有具体计算过程
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若4a-1/(a+2)(a-1)=m/(a+2) + n/(a-1),求m,n的值快点啦,要有具体计算过程
若4a-1/(a+2)(a-1)=m/(a+2) + n/(a-1),求m,n的值
快点啦,要有具体计算过程
若4a-1/(a+2)(a-1)=m/(a+2) + n/(a-1),求m,n的值快点啦,要有具体计算过程
4a-1/(a+2)(a-1)=m/(a+2) + n/(a-1),
两边同乘以a+2,得
(4a-1)/(a-1)=m+n(a+2)/(a-1)
令a=-2,得
-9/(-2-1)=m
即m=3
两边同乘以a-1,得
(4a-1)/(a+2)=m(a-1)/(a+2)+n
令a=1,得
(4-1)÷(1+2)=n
n=1
所以
m=3,n=1
4a-1/(a+2)(a-1)=m/(a+2) + n/(a-1)
=[m(a-1)+n(a+2)]/(a+2)(a-1)=[(m+n)a+2n-m]/(a+2)(a-1)
比较等式两边得:
4=m+n
-1=2n-m
解得:m=3,n=1
我们可以把右边的等式化为m(a-1)+n(a+2)/(a+2)(a-1),即[ma-m+na+2n]/(a+2)(a-1).→(m+n)a-(m-2n)=4a-1,
所以有m+n=4★,m-2n=1●,根据二元一次方程的求解方法,将★-●得到3n=3,即n=1,代进●得m=3.