1）有一道题“先化简再求值:{x

题目

1）有一道题“先化简再求值:{x
2）若x＞1,m=x-1/x,n=x/x+1,试比较m,n的大小关系 （3）分解因式：a^5-1/2a^3b^2+1/16ab^4 (4)若(4a-1)/(a+2)(a-10=m/(a+2)+n/(a-1),求m,n的值

答案

2) m-n=(x-1)/x-x/(x+1)=(x^2-1-x^2)/[x(x+1)]=-1/[x(x+1)]
∵x＞1
∴x(x+1)＞0
m-n<0
m3) a^5-1/2a^3b^2+1/16ab^4=a(a^4-1/2a^2b^2+1/16b^2)=a(a-1/4b)^2
4) (4a-1)/[(a+2)(a-10)]
=m/(a+2)+n/(a-1)
=[m(a-1)+n(a+2)]/[(a+2)(a-10)]
=[(m+n)a-m+2n]/[(a+2)(a-10)]
m+n=4,-m+2n=-1
m=3,n=1