CBSE Class 12 Maths 2010 Solved Paper

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Question : 11
Total: 29
Find all points of discontinuity of f, where f is defined as following:
f (x) =
{
\x\+3x3
2x3<x<3
6x+2x3

OR
Find
dy
dx
, if y = (cosx)x+(sinx)
1
x

Solution:  
Here, f (x) =
{
x +3x3
2x3<x<3
6x+2x3

The function is defined on all the points and hence continuous possible points ofdiscontinuity are 3 and -3 . We need to check the continuity of the function at twopoints x = 3 and x = -3.
Case 1: For x = -3, f(-3) = -(-3) + 3 = 6
LHL = lim
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