where A is the region between y=x and y=3x-x^2
我把它寫成∫∫x^2-xy dydx [x in [0,2] y in [3x-x^2,x] ]
不知道對不對
更新1:
x in [0,2] y=x 為什麼在y=3x-x^2之上呢