求不定积分∫[(x^2-9)^(1⼀2)]dx⼀(x^2)

2024-12-25 18:51:33
推荐回答(2个)
回答1:

当x>3时,令x=3secu,则(x^2-9)^(1/2)=3tanu,dx=3secu*tanudu
原式=∫ 3tanu/[9(secu)^2]*3secu*tanu du
=∫ (tanu)^2/(secu) du
=∫ (secu)^2-1]/(secu) du
=∫ secudu -∫ cosudu
=ln|secu+tanu|-sinu+C
=ln|x/3+√(x^2-9)/3|+√(x^2-9)/x^2+C
=ln|x+√(x^2-9)|+√(x^2-9)/x^2+C1

回答2:

解:∫[(x^2-9)^(1/2)]dx/(x^2)=∫[(x^2-9)^(1/2)]dx(x²-9)=2/3[(x^2-9)^(3/2) +c