JEE Main20207 Jan 2020Morning ShiftMathematicsApplication of DerivativesActual
Let the function , f : - 7 , 0 → R be continuous on - 7 , 0 and differentiable on - 7 , 0 . If f - 7 = - 3 and f ' x ≤ 2 for all x ∈ - 7 , 0 , then for all such functions f , f - 1 + f 0 lies in the interval
Options
- A- ∞ , 20
- B- 3 , 11
- C- ∞ , 11
- D- 6 , 20
Correct answer
A. - ∞ , 20
Step-by-step solution
Lets use LMVT for x ∈ - 7 , - 1 f - 1 - f - 7 - 1 + 7 ≤ 2 f - 1 + 3 6 ≤ 2 ⇒ f - 1 ≤ 9 Lets use LMVT for x ∈ - 7 , 0 f 0 - f - 7 0 + 7 ≤ 2 f 0 + 3 7 ≤ 2 ⇒ f 0 ≤ 11 ∴ f 0 + f - 1 ≤ 20