用洛必达法则求下列极限(1)lim(x→0^+)lntan7x/lntan2x(2)lim(x→0)xcot2x

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用洛必达法则求下列极限(1)lim(x→0^+)lntan7x/lntan2x(2)lim(x→0)xcot2x

用洛必达法则求下列极限(1)lim(x→0^+)lntan7x/lntan2x(2)lim(x→0)xcot2x
用洛必达法则求下列极限
(1)lim(x→0^+)lntan7x/lntan2x
(2)lim(x→0)xcot2x

用洛必达法则求下列极限(1)lim(x→0^+)lntan7x/lntan2x(2)lim(x→0)xcot2x
(1)lim(x→0^+)lntan7x/lntan2x
=lim [7(sec7x)^2 / tan7x ] / [2(sec2x)^2 / tan2x ]
=lim [7(sec7x)^2 *tan2x] / [2(sec2x)^2* tan7x ] 罗比达法则
=lim [7(sec7x)^2 *2x] / [2(sec2x)^2* 7x ] 等价替换
lim [7 *2] / [2* 7 ] =1
(2)lim(x→0)xcot2x
=lim[ x*cos 2x]/sin2x
=limx/sin2x 罗比达法则
=lim1/2cos2x
=1/2

1.=1
2.=1/2