JEE 2023 — Mathematics PYQ
JEE | Mathematics | 2023Let f(x)=2x+tan−1x and g(x)=loge(1+x2+x), x∈[0,3]. Then
Choose the correct answer:
- A.
minf(x)=1+maxg′(x)
- B.
\max f(x) > \max g(x)
(Correct Answer) - C.
there exist 0 < x_1 < x_2 < 3 such that f(x) < g(x), \forall \in (x_1, x_2)
\max f(x) > \max g(x)
Explanation
Solution
Differentiate:
f′(x)=2+1+x21 (Value range: [2.1,3] since max is 2+1 and min is 2+101).
g′(x)=1+x21 (Value range: [101,1]).
Check Options:
f′(x) is always greater than g′(x) for x∈[0,3]. Since f(0)=g(0)=0 and f grows faster, f(x) > g(x) for all x > 0.
maxf(3)=6+tan−1(3)≈7.25.
maxg(3)=loge(10+3)≈loge(6.16)≈1.82.
Clearly, \max f(x) > \max g(x).
Correct Option: (2)
Explanation
Solution
Differentiate:
f′(x)=2+1+x21 (Value range: [2.1,3] since max is 2+1 and min is 2+101).
g′(x)=1+x21 (Value range: [101,1]).
Check Options:
f′(x) is always greater than g′(x) for x∈[0,3]. Since f(0)=g(0)=0 and f grows faster, f(x) > g(x) for all x > 0.
maxf(3)=6+tan−1(3)≈7.25.
maxg(3)=loge(10+3)≈loge(6.16)≈1.82.
Clearly, \max f(x) > \max g(x).
Correct Option: (2)

