计算题 38.若∣y∣≤1,求∫-11∣x—y∣exdx.
【正确答案】原式=∫-1y(y-x)exdx+∫y1(x-y)exdx
=y∫-1yexdx-∫-1yxexdx+∫y1xexdx-y∫y1eydx
=y(ey-e-1)-xex-1y+∫-1yexdx+xexy1-∫y1exdx-y(e-ey)
=yey-ye-1-yey—e-1+ey-e-1+e-yey-e+ey-ey+yey
=2ey—y(e+e-1)-2e-1
【答案解析】