It is not clear if the denominator of the ratio is just x
or is (x+tan x).
This thing must be specified with the help
of the brackets.
If the denominator of the ratio is
x:
lim [sin(x)/x+tan(x)] = lim [sin(x)/x] + lim
tan(x)
lim [sin(x)/x] is an elementary limit and the result
is1.
We'll calculate lim tan
x.
We'll substitute x by the value
0.
lim tan x = tan 0 = 0
So,
the limit is:
lim [sin(x)/x+tan(x)] = 1 + 0 =
1
Now, if the denominator is
(x+tan x), we'll calculate the limit:
lim
[sin(x)/(x+tanx)] = sin 0/(x + tan 0)
lim
[sin(x)/(x+tanx)] = 0/0
"0/0" is an
indetermination
We'll use l'hospital rule. We'll
differentiate separately numerator and denominator.
(sinx)'
= cos x
(x+tanx)' = 1 + 1/(cos
x)^2
lim [sin(x)/(x+tanx)] = lim
(sinx)'/(x+tanx)'
lim (sinx)'/(x+tanx)' = lim cos x/[1 +
1/(cos x)^2]
We'll substitute x by
0:
lim cos x/[1 + 1/(cos x)^2] =cos 0/[1 + 1/(cos
0)^2]
cos 0/[1 + 1/(cos 0)^2] = 1/(1+1) =
1/2
lim
[sin(x)/(x+tanx)] =
1/2
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