Limit Continuity and Differentiability 4 Question 10

10. A discontinuous function y=f(x) satisfying x2+y2=4 is given by f(x)=.

(1982,2M)

Analytical & Descriptive Questions

Determine a and b such that f(x) is continuous at x=0.

(1994, 4M)

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Answer:

Correct Answer: 10. a=23,b=e2/312.a=8

Solution:

  1. f(x)=[x]sinπ[x+1]

We know that, [x] is continuous on RI, where I denotes the set of integers and sinπ[x+1] is discontinuous for [x+1]=0.

0x+1<11x<0

Thus, the function is defined in the interval.

Clearly, RHL (at x=1)=1/2 and LHL ( at x=1)=1/2 Also,

f(x)=1/2

f(x) is continuous for all x[0,2].

On differentiating Eq. (i), we get

Clearly, RHL (at x=1 ) for f(x)=1

and LHL (at x=1 ) for f(x)=1

Also,

f(1)=1

Thus, f(x) is continuous for all x[0,2].

Again, differentiating Eq. (ii), we get

Clearly, RHL (at x=1)LHL( at x=1 )

Thus, f(x) is not continuous at x=1.

or f(x) is continuous for all x[0,2]1.



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