第1个回答 2011-11-19
1、∫(2-3x)^3/2 dx
=(-1/3)∫(2-3x)^3/2 d(2-3x)
=(-1/3)(2-3x)(3/2+1)/(3/2+1)+C
=(2/15)(2-3x)^(5/2)+C.
2、∫a^3x dx(a>0,a≠1)
=(1/3)∫a^(3x)d(3x)
=(1/3)a^(3x)lna+C.
3、∫x√(4-x^2) dx
=(-1/2)∫√(4-x^2) d(4-x^2)
=(-1/2)(4-x^2)^(1/2+1)/(1/2+1)+C
=(-1/3)(4-x^2)^(3/2)+C.
4、∫lnx/x dx
=∫lnx dlnx
=(1/2)(lnx)^2+C.
5、∫1/(3+2x) dx
=(1/2)∫d(3+2x)/(3+2x)
=(1/2)ln|3+2x|+C.
6、∫x^2dx/(x^2+3)
=∫(x^2+3-3)dx/(x^2+3 )
=∫dx-∫3dx/(x^2+3)
=x-(√3)∫d(x/√3)/[(x/√3)^2+1]
=x-√3(arctan(x/√3)+C。
7、∫dx/(4-x^2)
=∫dx/(2-x)(2+x)
=(1/4)∫dx/(2-x)+(1/4)∫dx/(2+x)
=(-1/4)∫d(2-x/)(2-x)+(1/4)∫d(2+x)/(2+x)
=-(1/4)ln|2-x|+(1/4)ln|2+x|+C
=(1/4)ln|(2+x)/(2-x)|+C.