The least value of k for which the function x^2 + kx + 1 is an in… - Vidyadip

MCQ

The least value of $ k $ for which the function ${x^2} + kx + 1$ is an increasing function in the interval $1 \leq x \leq 2$ is

A
$-4$
B
$-3$
C
$-1$
✓
$-2$

✓

Answer

Correct option: D.

$-2$

d
(d) To be increasing, $\frac{d}{{dx}}({x^2} + kx + 1) > 0$

$ \Rightarrow 2x + k > 0$ For $x \in (1,\,2)$, the least value of $k$ is $ -2.$

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