求下列极限(1)limx→+∞(x+ex)1x(2)limx→∞(sin2x+cos1x)x(3)limx→0(1+tanx1+sinx) 1x3

求下列极限(1)limx→+∞(x+ex)1x(2)limx→∞(sin2x+cos1x)x(3)limx→0(1+tanx1+sinx) 1x3.
2026年09月21日 02:18
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网友(1):


(1)

lim
x→+∞
(x+ex)
1
x
lim
x→+∞
e
ln(x+ex)
x
e
lim
x→+∞
ln(x+ex)
x
e
lim
x→+∞
1+ex
x+ex
e1=e.

(2)
令:y=
1
x
lim
x→∞
(sin
2
x
+cos
1
x
)x
lim
y→0
(sin2y+cosy)
1
y
=e
lim
y→0
ln(sin2y+cosy)
y
e
lim
y→0
2cos2y?siny
sin2y+cosy
e2


(3)
原式=
lim
x→0
(1+
tanx?sinx
1+sinx
)
1
x3
=
lim
x→0
[(1+
tanx?sinx
1+sinx
)
1+sinx
tanx?sinx
]
tanx?sinx
(1+sinx)x3

=e
lim
x→0
tanx?sinx
x3
=e
lim
x→0
sinx(1?cosx)
x3

=e
lim
x→0