应用洛必达法则,分子分母同时求导得到:原式=lim2∫(0~x)sin(t²)dt·sin(x²)/[x²sin(x³)]=2lim∫(0~x)sin(t²)dt/sin(x³)【应用等价无穷小代换:sin(x²)~x²】=2lim∫(0~x)sin(t²)dt/x³【应用等价无穷小代换:sin(x³)~x³】=2limsin(x²)/(3x²)【应用洛必达法则,分子分母同时求导】=2limx²/(3x²)【应用等价无穷小代换:sin(x²)~x²】=2/3