Q92 / 160 · AP EAMCET 2024 (20 May Shift 2) · Mathematics
Equation of a tangent line of the parabola $y^2=8 x$, which passes through the point $(1,3)$ is
- Correct answerA$y=2 x+1$
- B$2 y=x+5$
- C$y=-2 x+5$
- D$2 y=3 x+3$
Solution
Equation of tangent to parabola $y^2=8 x$ is
$y=m x+\frac{2}{m}$
It passes through $(1,3)$ $\Rightarrow 3=m+\frac{2}{m} \Rightarrow m=1,2$ $\therefore$ Tangents are $y=x+2$ and $y=2 x+1$
It passes through $(1,3)$ $\Rightarrow 3=m+\frac{2}{m} \Rightarrow m=1,2$ $\therefore$ Tangents are $y=x+2$ and $y=2 x+1$
Hence, the correct answer is option: 'A'.