原极限=lim(x→0)[e^x/2sec²2x]=lim(x→0)[e^x·cos²2x/2]=½ 洛必达
∫dx/(1-2x)=-½∫d[1/(1-2x)]=-½ln|1-2x|+C
S=∫(0,1)eˣdx=eˣ|(0,1)=e-eº=e-1
