NCERT Class XI Mathematics - Limits and Derivatives - Solutions

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Question : 22
Total: 72
lim
x
π
2
tan2x
x
π
2
Solution:  
We have,
lim
x
π
2
tan2x
x
π
2
(0/0 form)
Put x =
π
2
+ y; if x →
π
2
⇒ y → 0
lim
y0
tan2(
π
2
+y
)
π
2
+y
π
2
=
lim
y0
tan(π+2y)
y
= (
lim
x0
tan2y
2y
)
× 2 = 2.
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