If m and n respectively are the number of local maximum and local minimum points of the function f(x)=∫0x22+ett2−5t+4dt, then the ordered pair (m,n) is equal to
(A)(3,2)
(B)(2,3)✓ Correct
(C)(2,2)
(D)(3,4)
Answer: (B)
Solution
Using Leibniz rule: f′(x)=2+ex2(x4−5x2+4)⋅2x=2+ex22x(x2−1)(x2−4)=2+ex22x(x−1)(x+1)(x−2)(x+2)
The critical points are x=−2,−1,0,1,2. Analyzing the sign changes:
At x=−2: changes from − to + (local minimum)
At x=−1: changes from + to − (local maximum)
At x=0: changes from − to + (local minimum)
At x=1: changes from + to − (local maximum)
At x=2: changes from − to + (local minimum)
Therefore, m=2 (local maxima) and n=3 (local minima).
Answer: (B)
JEE Main · 2022 · 27 Jun 2022 · Shift 2 · Single correct option