If the roots of the equation $3 x^2+4 k x+3=0$ are non-real, then $\mathrm{k}$ lies in the interval

If the roots of the equation $3 x^2+4 k x+3=0$ are non-real, then $\mathrm{k}$ lies in the interval
  1. $\left[-2, \frac{-3}{2}\right]$
  2. $\left[\frac{3}{2}, 2\right]$
  3. $\left[\frac{-3}{2}, \frac{3}{2}\right]$
  4. $(2,3)$

Solution

Given: $3 \mathrm{x}^2+4 \mathrm{kx}+3=0$ Above eq ${ }^{\mathrm{n}}$ has non-real roots if $ \begin{aligned} & (4 \mathrm{k})^2-4 \times 3 \times 3 < 0 \\ & \Rightarrow 16 \mathrm{k}^2-36 < 0 \\ & \Rightarrow \mathrm{k}^2 < \frac{9}{4} \\ & \Rightarrow-\frac{3}{2} < \mathrm{k} < \frac{3}{2} \end{aligned} $ $\Rightarrow \mathrm{k}$ lies in the interval $\left(-\frac{3}{2}, \frac{3}{2}\right)$

Asked in: AP EAMCET 2023 (18 May Shift 2)

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