limits

Lim (1/x2-cot2x)
x→0

5 Answers

1357
Manish Shankar ·

(1-x2cot2x)/x2 Applying L'Hospital
=-cot2x+xcotxcosec2x
=(cosx/sinx)(x/sin2x - cosx/sinx)
=(cosx/sin3x)(x-sinxcosx)=(cosx/sin3x)(x-sin2x/2)
Applying limits wherever possible and then applying L Hospital

(1-cos2x)/3sin2x=2sin2x/3sin2x=2/3

1
sindhu br ·

(1-x2cot2x)/x2
L'Hospital cant be applied becuz numerator and denominator are not tending to 0

1
yes no ·

@above
arey simplify it na in terms of cos and sin..u will see that its a 0/0 form

1
gordo ·

u can also use series expansion to do it,

[sin2x-x2cos2x]/x2sin2x

we have[\left(x-\frac{x^{3}}{3!} \right)^{2}-x^{2}\left(1-\frac{x^{2}}{2!} \right)^{2}}]/[x^{2}\left(x-x^{3}/3! \right)^{2}]

applying binomial theoram,

= [x^{2}(1-2x^{2}/3!)-x^{2}(1-2x^{2}/2!)]/[x^{4}(1-2x^{2}/3!)]

simplifying this we have 2/3 as the final answer

cheers!!

1357
Manish Shankar ·

[(1-(x/tanx)2]/x2

I considered (x/tanx) tending to 1 and hence applied L'Hospital

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