y=x²-2
y=x
先求交点
x²-2=x
x²-x-2=0
(x-2)(x+1)=0
得 x=2 或 x=-1
∫x-(x²-2)dx
=∫-x²+x+2 dx [-1,2]
=-x³/3+x²/2+2x [-1,2]
=(-8/3+2+4)-(1/3+1/2-2)
=10/3+7/6
=9/2