x^4/(1-x^4) 1/(1-x^2)这两个函数的原函数(即积分)怎么算
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x^4/(1-x^4) 1/(1-x^2)这两个函数的原函数(即积分)怎么算
x^4/(1-x^4) 1/(1-x^2)这两个函数的原函数(即积分)怎么算
x^4/(1-x^4) 1/(1-x^2)这两个函数的原函数(即积分)怎么算
先算后面一个
1/(1-x^2)dx=0.5(1/(1-x) dx+1/(1+x) dx)=0.5(ln|1+x|-ln|1-x|)=0.5ln|(1+x)/(1-x)|
再算前面一个
x^4/(1-x^4)dx
=(1/(1-x^4)-1)dx
=(0.5/(1-x^2)+0.5/(1+x^2)-1)dx
0.5/(1-x^2)的积分可以用到上面那个
0.5/(1+x^2)的积分有公式的=arctanx
所以答案是
0.25ln|(1+x)/(1-x)|+0.5arctanx-x
(注:答案中的常数项C未写)
∫x^4/(1-x^4)dx=∫[-1+1/(1-x^4)]dx =x+1/2∫[1/(1-x^2)+1/(1+x^2)]dx =x+1/2* arctanx+1/4∫[1/(1-x)+...
全部展开
∫x^4/(1-x^4)dx=∫[-1+1/(1-x^4)]dx =x+1/2∫[1/(1-x^2)+1/(1+x^2)]dx =x+1/2* arctanx+1/4∫[1/(1-x)+1/(1+x)]dx =x+1/2* arctanx+1/4ln|(1+x)/(1-x)|+C 2. ∫1/(1-x^2)dx =1/2∫[1/(1-x)+1/(1+x)]dx =1/2ln|(1+x)/(1-x)|+C
收起