Q87 / 160 · TS EAMCET 2023 (14 May Shift 1) · Mathematics
For $\ell \in \mathbb{R}$, the equation $(2 \ell-3) \mathrm{x}^2+2 \ell \mathrm{xy}-\mathrm{y}^2=0$ represents a pair of distinct lines
- Aonly whən $\ell=0$
- Bfor all values of $\ell \in(-3,1)$
- Cfor all values of $\ell \in \mathbb{R}-(0,1)$
- Correct answerDfor all values of $\ell \in \mathbb{R}-[-3,1]$
Solution
$a x^2+2 \mathrm{~h} x y+\mathrm{b} y^2=0$
represents distinct lines if
$$
\begin{aligned}
& h^2-a b>0 \therefore l^2+(2 l-3)>0 \\
& l^2+2 l-3>0 \\
& (l+3)(l-1)>0 \\
& \therefore l \in(-\infty,-3) \cup(1, \infty) \text { or } l \in \mathrm{R}-[-3,1]
\end{aligned}
$$
Hence, the correct answer is option: 'D'.