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Q.

Let  f(x)={max.{t3t2+t+1.0tx},0x1min.{3t,1<tx}    1<x2       and   g(x)={max.{38t4+12t332t2+1,0tx},   0x<1min.{38t+132sin2πt+58,1tx}     1x2

Which of the following options are does not holds good with respect to the given functions  f(x)  and  g(x)

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a

limx1fog(x)>limx1+gof(x)

b

Let  Z(x)=ddx(f(x)g(x))and  Y(x)=ddx(g(x)f(x)) then  Z(x) and  Y(x) vanish simultaneously at no real value of  x

c

Number of solutions of  f(x)=g(x) is 4

d

f(x)  is continuous  x[0,2]  and not differentiable at atmost 2 points in     [0,2]

answer is D.

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Detailed Solution

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consider f(x) in [0,1]
f1(t)=3t22t+1>0t(0,1)fisin(0,1)
Maximum occurs at  t=x.
And hence  f(x)is{x3x2+x+1       0x13x                           1<x2
Again consider   g(x)=in[0,1)
g(t)=38t4+12t332t2+1            g1(t)=32t3+3t23t=32t(t2+t2)=32t(t1)(t+2)
g(t) decreases in [0,1)
maximum occurs when t=0 and g(0)=1
again consider g(x) function in [1,2]
g(t)=38t+132sun2πt+58             g1(t)=38+π32sin(2πt)>0tR
G is an increasing function in [1,2]
 minimum occurs when t=1   And g(1)=1
hence  g(x)={1   0x<11    1<x2=x[0,2]
f(x) is continuous but not differentiable at x=1 (B)
limxxfog(x)=f(1)andlimxx+gof(x)=1alsof(1)>1  (A)         Z(x)=ddxf(x)g(x)=ddxf(x)1x[0,1)(1,2]        f1(x)x[0,1)(1,2]           &Y(x)=ddxg(x)f(x)=ddx1f(x)=0x[0,1)(1,2]
Hence the function Y(x)and Z(x) can vanish simultaneously at   which is not possible for any real X.

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Let  f(x)={max.{t3−t2+t+1.0≤t≤x},0≤x≤1min.{3−t,1<t≤x}    1<x≤2       and   g(x)={max.{38t4+12t3−32t2+1,0≤t≤x},   0≤x<1min. {38t+132sin2πt+58,1≤t≤x}     1≤x≤2Which of the following options are does not holds good with respect to the given functions  f(x)  and  g(x)