Test Index

NCERT Class XI Mathematics - Limits and Derivatives - Solutions

© examsnet.com
Question : 49
Total: 72
1+
1
x
1−
1
x
Solution:  
Let f (x) =
1+
1
x
1−
1
x
 ... (i)
Differentiating (i) with respect to x, we get
d
dx
 (f (x)) =
(1−
1
x
)(1+
1
x
)−(1+
1
x
)(1−
1
x
)
(1−
1
x
)2
=
(1−
1
x
)(−
1
x2
)−(1+
1
x
)(
1
x2
)
(1−
1
x
)2

=
−
1
x2
+
1
x3
−
1
x2
−
1
x3
(1−
1
x
)2
=
−
2
x2
(1−
1
x
)2
=
−
2
x2
(x−1)2
x2
 =
−2
(x−1)2
 , x ≠ 0 , 1
© examsnet.com
Go to Question:
Prev Question
Next Question