limx→0 x/根号(1-cosx)

问题描述:

limx→0 x/根号(1-cosx)

答案根2
1-cosx~1/2 x^2 (x→0)

解:
用洛必达法则
limx→0 x/根号(1-cosx)=limx→0 2根号1-cosx
所以limx→0 x/根号(1-cosx)=limx→0 2根号1-cosx=0

解 x x x 2 (x/2) 2
lim----------------- =lim ------------------------- =lim ------------------- =lim--------------------= -----=√2
x→0 √(1-cosx) x→0 √(1-(1-2sin²(x/2))) x→0 √(2sin²(x/2)) x→0 √2*sin(x/2) √2

√2, 1-cosx~1/2x^2 (x→0)

lim(x→0) x/√(1-cosx)
=lim(x→0) x/√2sin ²x/2
=lim(x→0) 2/√2* (x/2)/(sin x/2)
= 2/√2
=√2
【数学辅导团】为您解答

x→0,1-cosx~(X^2)/2
limx→0 x/根号(1-cosx)=√2