JEE Main20211 Sep 2021Evening ShiftMathematicsFunctionsActual
The range of the function f ( x ) = log 5 3 + cos 3 π 4 + x + cos π 4 + x + cos π 4 - x - cos 3 π 4 - x is :
Options
- A1 5 ,   5
- B[ 0 ,   2 ]
- C( 0 ,   5 )
- D[ - 2 ,   2 ]
Correct answer
B. [ 0 ,   2 ]
Step-by-step solution
f ( x ) = log 5 ( 3 - 2 sin x + 2 cos x ) - 2 ≤ ( - 2 sin x + 2 cos x ) ≤ 2 ⇒ 1 ≤ ( 3 - 2 sin x + 2 cos x ) ≤ 5 ⇒ log 5 1 ≤ f ( x ) ≤ log 5 5 ⇒ 0 ≤ f ( x ) ≤ 2