e5.证明广义积分ebc当p>0时收敛, 当p<0时发散 Proof r"e“=mnea=lm/-y P e pb m D,b⊥0 e b→+a 0,p<0 即当尸>0时收敛,当p<0时发散ex5. 证明广义积分 + − a px e dx当 p  0时收敛， 当 p  0时发散. Proof.  + − a px e dx  − →+ = b a px b lim e dx b a px b p e       = − − →+  lim       = − − − →+  p e p e pa pb b lim         = − , 0 , 0 p p p e ap 即当p  0时收敛，当p  0时发散