If \(3 a+5 b+6 c=0\) then the family of lines \(a x+b y+c=0\) pass through the fixed point

If \(3 a+5 b+6 c=0\) then the family of lines \(a x+b y+c=0\) pass through the fixed point
  1. \(\left(\frac{5}{6}, \frac{1}{2}\right)\)
  2. \(\left(\frac{1}{2}, \frac{1}{3}\right)\)
  3. \(\left(\frac{1}{3}, \frac{1}{2}\right)\)
  4. \(\left(\frac{1}{2}, \frac{5}{6}\right)\)

Solution

Given equation of family of lines \(\begin{aligned} & a x+b y+c=0 \\ & \because \quad 3 a+5 b+6 c=0, \text { so } a x+b y-\frac{3 a+5 b}{6}=0 \\ & \Rightarrow \quad 3 a(2 x-1)+b(6 y-5)=0 \end{aligned}\) So, the family of lines passes through the fixed point \(\left(\frac{1}{2}, \frac{5}{6}\right)\). Hence, option (d) is correct.

Asked in: AP EAMCET 2020 (21 Sep Shift 2)

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