Continuity and differentiablilty

1) The no. of points at which the function f(x) = max {a-x , a+x, b},
- ∞ < x < ∞ , 0 <a < b cannot be differentiable is:
(a)2 (b) 3 (c)1 (d) 0

2) If f(x) = sin (2∩ [ ∩2 - x] )5 +[x] 2 ; where [.] denotes the greatest inegral function then f(x) is
(a) discontinous at some x
(b) continous at all x , but the deriviative f ' (x) does not exists for some x
(c) f ' (x) exists for all x , but f '' (x) does not exists
(d) f '' (x) exists for all x

7 Answers

62
Lokesh Verma ·

For question 1, I always suggest use of graphss...

ddraw the graph of f(x) you will have three different straightlines...

a-x, a+x and b

Draw the line which is the maximum.. That will give the graph of f(x)

Try it after this hint..

62
Lokesh Verma ·

Question 2

Answer this : Is the part inside sin an integer multiple of 2pi???

what is teh sin of an integer multiple of pi??

So what is the value of f(x) ??

1
Little Angel ·

For ques 2) yes the part inside sin is an integral multiple of 2 pi

f(x) should be zero

1
Little Angel ·

For ques 1)Nishant bhayiya , should the graph be like this????

My ans is coming (a)

1
chinmay saxena ·

yeah the answer is definitely 2,,,coz in the graph u see there r two sharp points,,,one is (a-b,b) and other is (b-a,b),,,hope i helped u

62
Lokesh Verma ·

yes sabitha.. you are correct..

only one thing.. your graph suggests that a=b/2

In principle what you have done is correct for both :)

1
Little Angel ·

Thankyou Nishant bhayiya

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