(1/2)arctan(x-1)+(1/2)x(x-1)/(x^2-2x+2)+C
解题过程如下:
I = ∫xdx/(x^2-2x+2)^2 = ∫xdx/[(x-1)^2+1]^2,
令 x-1= tant, 则 x=1+tant, dx=(sect)^2dt,
I = ∫xdx/[(x-1)^2+1]^2 = ∫(1+tant)dt/(sect)^2
= ∫[(cost)^2+sintcost]dt
= ∫[1/2+(1/2)cos2t+sintcost]dt
= t/2+(1/4)sin2t+(1/2)(sint)^2+C
= (1/2)arctan(x-1)+(1/2)x(x-1)/(x^2-2x+2)+C
记作∫f(x)dx或者∫f(高等微积分中常省去dx),即∫f(x)dx=F(x)+C。其中∫叫做积分号,f(x)叫做被积函数,x叫做积分变量,f(x)dx叫做被积式,C叫做积分常数或积分常量,求已知函数的不定积分的过程叫做对这个函数进行不定积分。
常用积分公式:
1)∫0dx=c
2)∫x^udx=(x^(u+1))/(u+1)+c
3)∫1/xdx=ln|x|+c
4)∫a^xdx=(a^x)/lna+c
5)∫e^xdx=e^x+c
6)∫sinxdx=-cosx+c
7)∫cosxdx=sinx+c
I = ∫xdx/(x^2-2x+2)^2 = ∫xdx/[(x-1)^2+1]^2,
令 x-1= tant, 则 x=1+tant, dx=(sect)^2dt,
I = ∫xdx/[(x-1)^2+1]^2 = ∫(1+tant)dt/(sect)^2
= ∫[(cost)^2+sintcost]dt
= ∫[1/2+(1/2)cos2t+sintcost]dt
= t/2+(1/4)sin2t+(1/2)(sint)^2+C
= (1/2)arctan(x-1)+(1/2)x(x-1)/(x^2-2x+2)+C