Question

Tìm M thuộc Oy sao khoảng cách từ M đến Δ: 3x+4y-6=0 bằng \(\frac{7}{5}\)

Answer 1

Gọi \(M\left(0;m\right)\)

\(d\left(M;\Delta\right)=\frac{\left|3.0+4m-6\right|}{\sqrt{3^2+4^2}}=\frac{7}{5}\)

\(\Leftrightarrow\left|4m-6\right|=7\Rightarrow\left[{}\begin{matrix}4m-6=7\\4m-6=-7\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}m=\frac{13}{4}\\m=-\frac{1}{4}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}M\left(0;\frac{13}{4}\right)\\M\left(0;-\frac{1}{4}\right)\end{matrix}\right.\)