MHT CET202311 May 2023Evening ShiftMathematicsFunctionsActual
If f (x)= 3 x+4 5 x-7 and g (x)= 7 x+4 5 x-3 , then f ( g (x))=
Options
- Ax^3+1 x^2+2
- B41 x
- Cg(f(x))
- D5 x-7 41
Correct answer
C. g(f(x))
Step-by-step solution
aligned f(g(x)) & =f ( 7 x+4 5 x-3 ) & = 3 ( 7 x+4 5 x-3 )+4 5 ( 7 x+4 5 x-3 )-7 & = 21 x+12+20 x-12 35 x+20-35 x+21 & = 41 x 41 & =x aligned aligned & Now, g ( f (x))= g ( 3 x+4 5 x-7 ) &= 7 ( 3 x+4 5 x-7 )+4 5 ( 3 x+4 5 x-7 )-3 &= 21 x+28+20 x-28 15 x+20-15 x+21 &= 41 x 41 &=x & f ( g (x))= g ( f (x)) aligned