Math, asked by vishwanath2k4, 10 months ago

4.
If the parabola y2 = ax passes through
(1, 2) then the equation of the directrix is
1)x+1=0 2)x+2=0 3)x+3=0 4)x+4=0​

Answers

Answered by MaheswariS
2

\textbf{Given:}

\textsf{The parabola}\;\mathsf{y^2=ax}\;\textsf{passes through (1,2)}

\textbf{To find:}

\textsf{Directrix of the given parabola}

\textbf{Solution:}

\textsf{Since the parabola}\;\mathsf{y^2=ax}\;\textsf{passes through (1,2),}

\textsf{we have}\;\mathsf{2^2=a(1)}

\implies\mathsf{a=4}

\therefore\textsf{The equation of parabola becomes}

\boxed{\mathsf{y^2=4x}}

\textsf{We know that, directrix of the parabola}\;\mathsf{y^2=4ax}\;\textsf{is x=-a}

\mathsf{Here,\;4a=4}

\implies\mathsf{a=1}

\therefore\mathsf{The\;equation\;of\;dirctrix\;is\;x=-a}

\implies\mathsf{x=-1}

\implies\boxed{\mathsf{x+1=0}}

\textbf{Answer:}

\mathsf{Option\;(1)\;is\;correct}

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