On the intervl (1,3), the function f(x) = 3x + 2 x is - Vidyadip

MCQ

On the intervl $ (1,3)$, the function $f(x) = 3x + {2 \over x}$ is

A
Strictly decreasing
✓
Strictly increasing
C
Decreasing in $ (2, 3) $ only
D
Neither increasing nor decreasing

✓

Answer

Correct option: B.

Strictly increasing

b
(b) $f(x) = 3x + \frac{2}{x}$

==> $f'(x) = 3 - \frac{2}{{{x^2}}}$

Clearly $f'(x) > 0$ on the interval $(1, 3)$

$f(x)$ is strictly increasing.

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