Question

求定积分上限是负1下限是0 x乘e的x次方dx

Answer 1

∫(0,-1)xe^xdx [(0,-1)表示下限是0（在前）,上限是-1（在后）]
=-∫(-1,0)xde^x
=- { [xe^x(-1.0)]-∫(-1,0)e^xdx}
=∫(-1,0)e^xdx+[xe^x(-1,0)]
=e^x(-1,0)+[xex(-1,0]
=e^0-e^(-1)+[-e^(-1)]
=1-1/e-1/e
=1-2/e