联立

y＝x2+2 y＝3x

，解得x₁=1，x₂=2
∴S=∫₀¹（x²+2-3x）d_x+∫₁²（3x-x²-2）d_x=

[ 1 3 X3+2X− 3 2 X2]

10

+

[ 3 2 X2− 1 3 X3−2X]

21

=1