NCERT Class XI Mathematics - Limits and Derivatives - Solutions
© examsnet.com
Question : 37
Total: 72
For the function
f (x) =
+
+ ... +
+ x + 1.
Prove that f ′(1) = 100 f ′(0).
f (x) =
Prove that f ′(1) = 100 f ′(0).
Solution:
We have
f (x) =
+
+ ... +
+ x + 1. ... (i)
Differentiating (i) with respect to x we get
f' (x) =
+
+ ... +
+ 1
⇒ f' (x) =1 99 + 1 98 + ... + x + 1
At x = 1
f' (1) =1 99 + 1 98 + ... + 1 + 1 = 100
and f' (0) = 0 + 0 + ... + 0 + 1 = 1
Hence f ′(1) = 100 f ′(0).
f (x) =
Differentiating (i) with respect to x we get
f' (x) =
⇒ f' (x) =
At x = 1
f' (1) =
and f' (0) = 0 + 0 + ... + 0 + 1 = 1
Hence f ′(1) = 100 f ′(0).
© examsnet.com
Go to Question: