Question

If he point $(0,0)$, and $(1,2)$ and $(x,y)$ are collinear, then find the relation between $x$ and $y$

Answer 1

As points are collinear, therefore there, $△=0$

$△=\left[\begin{array}{ccc}0& 0& 1\\ 1& 2& 1\\ x& y& 1\end{array}\right]=0$

Solving this determinant, we get

$⟹0+0+1(y-2x)=0$

Hence, $y=2x$