洛必达法则,得
原式=lim(x->0)2∫(0,x)(e^(t^2)dt ×e^(x^2))/(xe^(2x^2))
=lim(x->0)2∫(0,x)(e^(t^2)dt /x
=lim(x->0)2(e^(x^2)/1
=2×e^0
=2