基础的定积分1∫(1+x²)dx = (1+ 1³/3) - (0+0³/3) = 4/30
y=1+x²y=0且0所以面积S=∫(0到1)(1+x²-0)dx=x+x³/3(0到1)=(1+1/3)-(0+0)=4/3
