2x/(1-x ^2)的导数为何是2(1+x^2)/(1-x^2)^2设m=2x,n=1-x^2y'=(m/n)'=m'n-n'm=2(1-x^2)-(-2x)*2x-=2+2x^2为啥正确答案会有个分母呢,不懂啊

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2x/(1-x ^2)的导数为何是2(1+x^2)/(1-x^2)^2设m=2x,n=1-x^2y'=(m/n)'=m'n-n'm=2(1-x^2)-(-2x)*2x-=2+2x^2为啥正确答案会有个分母呢,不懂啊

2x/(1-x ^2)的导数为何是2(1+x^2)/(1-x^2)^2设m=2x,n=1-x^2y'=(m/n)'=m'n-n'm=2(1-x^2)-(-2x)*2x-=2+2x^2为啥正确答案会有个分母呢,不懂啊
2x/(1-x ^2)的导数为何是2(1+x^2)/(1-x^2)^2
设m=2x,n=1-x^2
y'=(m/n)'=m'n-n'm=2(1-x^2)-(-2x)*2x-=2+2x^2
为啥正确答案会有个分母呢,不懂啊

2x/(1-x ^2)的导数为何是2(1+x^2)/(1-x^2)^2设m=2x,n=1-x^2y'=(m/n)'=m'n-n'm=2(1-x^2)-(-2x)*2x-=2+2x^2为啥正确答案会有个分母呢,不懂啊
你公式记错了
应该是(m/n)'=(m'n-mn')/n^2

f(x)=ax²+bx+c
f(0)=c=0
f(1)=a+b+c=1
a(1+x)²+b(1+x)+c=a(1-x)²+b(1-x)+c
a=-1,b=2,c=0
f(x)=-x²+2x=-(x-1)²+1
f(x)≤1
mmax[f(x)]=f(n)=-n²+2n=n
min[f(x)]=f(m)=-m²+2m=m
m=0,n=1