積分による求積

   
\[y = -x^2+2x+0.1\] \[ \int_0^1 (-x^2+2x+0.1) dx = \left [ -\frac{x^3}{3} + x^2 + 0.1 x \right ]_{x=0}^{x=1}\] \[ = -\frac{1}{3}+1+0.1 = 7.6666\cdots\]