NDA2026MathematicsTrigonometric Ratios & IdentitiesActual
x+ 3 x is maximum when x is equal to
Options
- A2
- B3
- C4
- D6
Correct answer
B. 3
Step-by-step solution
Given expression is f(x) = x + 3 x Multiplying and dividing by 1^2 + ( 3 )^2 = 2 f(x) = 2 ( 1 2 x + 3 2 x ) f(x) = 2 ( 3 x + 3 x ) f(x) = 2 ( x - 3 ) The maximum value of ( x - 3 ) is 1 , which occurs when x - 3 = 0 x = 3 Answer: 3