TestHub
TestHub

Mathematics - Continuity - Differentiability Question with Solution | TestHub

MathematicsContinuity - DifferentiabilityDifferentiabilityMedium2 minPYQ_2020
MathematicsMediuminteger

Let the functions f:-1,1 and  g:-1,1-1,1 be defined by fx= 2x-1+2x+1 & gx=x-x, where x denotes the greatest integer less than or equal to x. Let fg:-1,1 be the composite function defined by fgx=fgx. Suppose c is the number of points in the interval -1,1 at which fg is not continuous, and suppose d is the number of points in the interval -1, 1 at which  fg is not differentiable. Then the value of c+d is _____________

Answer:
4
Solution:

fx=2x-1+2x+1=-4x,x<-122,-12x124x,x>12

gx=x

fgx=-4gx,gx<-122,-12gx124gx  gx>12

Graph of gx is

fgx=2,x-1,-120,124x+1x-12,04xx12,1

c=1 at x=0

d=3 at x=-12, 0, 12,

c+d=4.

Stream:JEE_ADVSubject:MathematicsTopic:Continuity - DifferentiabilitySubtopic:Differentiability
2mℹ️ Source: PYQ_2020

Doubts & Discussion

Loading discussions...