Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
MHT CET202019 Oct 2020Morning ShiftMathematicsFunctionsActual

If f: R R is given by f(x)=7 x+8 and f⁻¹(12)= k 7 , then the value of k is

Options

  1. A7
  2. B1
  3. C4
  4. D8

Correct answer

C. 4

Step-by-step solution

(C) We have f(x)=7 x+8=y ...(let) x = y -8 7 f ⁻¹( y )= y -8 7 f ⁻¹( x )= x -8 7 f ⁻¹(12)= 12-8 7 = 4 7 k =4

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