The function $f(x) = x + \frac{1}{x}$ has
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → local maxima at $x = -1$
Given $f(x) = x + \frac{1}{x}$.
Differentiate:
$f'(x) = 1 - \frac{1}{x^2}$
Setting $f'(x) = 0$:
$1 - \frac{1}{x^2} = 0$
$x^2 = 1$
$x = \pm 1$
Second derivative:
$f''(x) = \frac{2}{x^3}$
At $x = 1$: $f''(1) = \frac{2}{1^3} = 2 > 0$ (local minimum).
At $x = -1$: $f''(-1) = \frac{2}{(-1)^3} = -2 < 0$ (local maximum).
Local maxima occur at $x = -1$ with value:
$f(-1) = -1 + \frac{1}{-1} = -1 - 1 = -2$.