MHT CET202013 Oct 2020Evening ShiftMathematicsFunctionsActual

If f : R R , g: R R defined by f(x)=x²-3 x+4 and g(x)=2 x+1 , then the value of x for which f(x)=f g)(x) is

Options

A1, -2 3
B-1, 2 3
C1, 2 3
D-1, -2 3

Correct answer

B. -1, 2 3

Step-by-step solution

( fog )(x)=f[g(x)]=f(2 x+1)=(2 x+1)²-3(2 x+1)+4 =4 x²+4 x+1-6 x-3+4=4 x²-2 x+2 Given f(x)=(f g)(x) x²-3 x+4=4 x²-2 x+23 x²+x-2=0 3 x²+3 x-2 x-2=03 x(x+1)-2(x+1)=0 (x+1)(3 x-2)=0 x=-1, 2 3

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