Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main202225 Jun 2022Morning ShiftMathematicsDifferentiationActual

Let f : R → R be defined as f x = x 3 + x - 5 . If g x is a function such that f g x = x , ∀ x ∈ R , then g ' 63 is equal to ______

Options

  1. A49
  2. B1 49
  3. C43 49
  4. D3 49

Correct answer

B. 1 49

Step-by-step solution

Here, g f x = x as f x and g x are inverse of each other. Now, g ' f x f ' x = 1 ⇒ g ' f x = 1 f ' x               … i Now f x = 63     ⇒   x 3 + x - 5 = 63 ⇒     x 3 + x - 68 = 0 So x = 4 satisfies the above equation g ' 63 = 1 f ' 4 from i = 1 3 4 2 + 1 = 1 49

Practice Differentiation on Quantrex Academy →

More from Differentiation

Let R denote the set of all real numbers. Consider the polynomial function f: R R defined by f(x) = d¹⁰ dx¹⁰ ((x^2 - 1)¹⁰ ) , for all x R . Here d¹⁰ dx¹⁰ ((x^2 - 1)¹⁰ ) is the 10th 2026Let f(x) and g(x) be twice differentiable functions satisfying f''(x) = g''(x) for all x R , f'(1) = 2g'(1) = 4 and g(2) = 3f(2) = 9 . Then f(25) - g(25) is equal to : 2026Let f be a real polynomial of degree n such that f(x) = f'(x) f''(x) , for all x R . If f(0) = 0 , then 36 (f'(2) + f''(2) + ₀^2 f(x) ,dx ) is equal to: 2026Let f(x)=x³+x² f^ (1)+2 x f^ (2)+f^ (3), x R . Then the value of f^ (5) is: 2026Let R denote the set of all real numbers. Let f: R R and g: R (0,4) be functions defined by f(x)= _e (x^2+2 x+4 ) , and g(x)= 4 1+e^ -2 x Define the composite function f g⁻¹ by (f 2025Let f: R R be a twice differentiable function such that ( x y)(f(2 x+2 y)-f(2 x-2 y))=( x y )(f(2 x +2 y )+f(2 x -2 y )) , for all x , y R . If f^ (0)= 1 2 , then the value of 24 f 2025If _e y=3 ⁻¹ x , then (1-x^2 ) y^ -x y^ at x= 1 2 is equal to 2024Let f(x)=a x^3+b x^2+c x+41 be such that f(1)=40, f^ (1)=2 and f^ (1)=4 . Then a ^2+ b ^2+ c ^2 is equal to: 2024 Full Differentiation list All JEE Main PYQs