AP EAMCET20224 Jul 2022Morning ShiftMathematicsApplication of DerivativesActual
The maximum value of f x = x 4 + x + x 2 on [ - 1 , 1 ] is
Options
- A- 1 4
- B- 1 3
- C1 6
- D1 5
Correct answer
C. 1 6
Step-by-step solution
∵ f x = x 4 + x + x 2 On differentiating w.r.t. x , we get f ′ x = 4 + x + x 2 - x ( 1 + 2 x ) 4 + x + x 2 2 For maximum, put f ′ x = 0 ⇒ 4 - x 2 4 + x + x 2 2 = 0 Given x ∈ [ − 1 , 1 ] ⇒ x 2 ∈ [ 0 , 1 ] ⇒ 4 − x 2 > 0 ⇒ f ′ ( x ) is increasing in [ − 1 , 1 ] and its maximum value will be f ( 1 ) = 1 6 .