Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
MHT CET202014 Oct 2020Evening ShiftMathematicsFunctionsActual

If f(x)= 3 x+4 5 x-7 , x 7 5 g(x)= 7 x+4 5 x-3 , x 3 5 then (g f)(3)=

Options

  1. A-3
  2. B- 1 3
  3. C3
  4. D1 3

Correct answer

C. 3

Step-by-step solution

aligned (g f)(x) &=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 = 7(3 x+4)+4(5 x-7) 5(3 x+4)-3(5 x-7) = 41 x 41 =x (g f)(3) &=3 aligned

Practice Functions on Quantrex Academy →

More from Functions

If f : R A , defined by f ( x )= x + 3 x -1 , is an onto function then A = 2025Let g(x)=1+x-[x] and f(x)= cases -1, & x 0 cases ([x] ) denotes the greatest integer less than or equal to (x ). Then for all x , f ( g ( x ))= 2025The domain of the real valued function f(x)= 3 4-x^2 + ₁₀ (x^3-x ) is 2025A real valued function f: A B defined by f(x)= 4-x^2 4+x^2 x A is a bijection. If -4 A then A B= 2025Let [ x ] represent the greatest integer less than or equal to x , x = x -[ x ] , 2 =1.414 and 3 =1.732 . If f(x)= x+ [ x 1+x^2 ] is a real valued function, then f ( 2 )+ f (- 3 )= 2025If the range of the function f(x)=-3 x-3 is 3,-6,-9,-18 , then which one of the following is not in the domain of f ? 2025The domain of the function f(x)= _e ( 1 x^2-4 x+4 ) + ⁻¹ (x^2-2 ) is 2025Consider the following statements Statement-I : A function f : A B is said to be one-one if and only if f(x) f(y) x y Statement-II : A relation f: A B is said to be a function if x 2025 Full Functions list All MHT CET PYQs