Question

Let f:(0, ) ® R defined by f(x) = x + + cos x

then minimum value of f(x) is

• A. 6p – 1
• B. 10p – 1
• C. 3p – 1
• D. ) None of these

Answer 1

Answer: (A)

6p – 1

Answer 2

AM ³ GM

x + $\frac { 9 \pi ^ { 2 } } { x }$ ³ 6p

minimum value occurs at x = 3p same times value of cos x is – 1

$x + \frac { 9 \pi ^ { 2 } } { x }$ + cos x ³ 6p – 1