早教吧 育儿知识 作业答案 考试题库 百科 知识分享

∫x^3/9+x^2dx怎么求不定积分?

题目详情
∫x^3/9+x^2 dx 怎么求不定积分?
▼优质解答
答案和解析
令x^2=t
∫x^3/9+x^2 dx=1/2∫x^2/(9+x^2)dx^2
=1/2∫tdt/(9+t)
=1/2∫(9+t-9)dt/(9+t)
=1/2∫dt-9/2∫dt/9+t
=t/2-9In(9+t)/2
=x^2/x-(9/2)In(9+x^2)+C