求极限(1) lim(x→2)(3x²-2x-1)/(2x³-x²+5)(2)lim(x→正无穷)x³/e^x

问题描述:

求极限(1) lim(x→2)(3x²-2x-1)/(2x³-x²+5)(2)lim(x→正无穷)x³/e^x

(1) lim(x→2)(3x²-2x-1)/(2x³-x²+5)
=(12-4-1)/(16-4+5)=7/17
(2)lim(x→正无穷)x³/e^x
=lim3x²/e^x
=lim6x/e^x
=lim6/e^x
=0