JEE Main202225 Jun 2022Evening ShiftMathematicsApplication of DerivativesActual
Let f x = x - 1 x 2 - 2 x - 3 + x - 3 , x ∈ ℝ . If m and M are respectively the number of points of local minimum and local maximum of f in the interval 0 , 4 , then m + M is equal to _____.
Correct answer
0
Step-by-step solution
Given, f x = x - 1 x + 1 x - 3 + x - 3 f x = x - 3 x 2 , 3 ≤ x ≤ 4 x - 3 2 - x 2 , 1 ≤ x < 3 x - 3 x 2 , 0 < x < 1 f ' x = 3 x 2 - 6 x , 3 < x < 4 - 3 x 2 + 6 x + 2 , 1 < x < 3 3 x 2 - 6 x , 0 < x < 1 f ' 3 + > 0 f ' 3 - < 0 → Minimum f ' 1 + > 0 f ' 1 - < 0 → Minimum For x ∈ 1 , 3 , f ' x = 0 at one point → Maximum For x ∈ 3 , 4 ,   f ' x ≠ 0 For x ∈ 0 , 1 ,   f '