电影
= π/4 + (1/2)∫[1,1] 1/u du
=lim(3x^2)/x^2=3
=sinx|(0->π/4)+cosx|(0->π/4)-cosx|(π/4->π/2)-sinx|(π/4->π/2)
令t=1/u 变换(2)式得 f(1/x)= ∫ln(1/u)/(1+(1/u )^2) d(1/u ) u= 1→x
∫[1-2](t(1-t)×2t)dt
=lim(x->1)(lnx+1)/[lnx+1+1]
=[2+1/(x-1)+1/(x-1)]/{x[1+/(x×x-1)]}
=e2-3
= (1/2)∫ dx + (1/2)∫ (cosx-sinx)/(sinx+cosx) dx,令u=sinx+cosx,du=(cosx-sinx)dx
手机
B=∫sinx/(sinx+cosx)dx
A(x^4+2x^2+1)+(Bx+C)(x^3-x^2+x-1)+(Dx^2+Ex-Dx-E)=1
=sinx+(1/2)∫sin2xdx
f(x)=∫[1,x] ln(1+t)/t dt 令u=1/t
=lim(x)[3cos^2(x)sinx]/2[1/(1+x)^2+1/(1+x)-2]
=∫(0-π/2)(1-sin2x)2·(sinx)2d(sinx)
=lim(3x^2)/x^2=3
a+b=1,a-b=0,a=b=1/2,
= (1/2)(lnt)^2 |[1→1/x]