If $l, m, n$ are in arithmetic progression, then the straight line $l x+m y+n=0$ will pass through the point
If $l, m, n$ are in arithmetic progression, then the straight line $l x+m y+n=0$ will pass through the point
$(-1,2)$
$(1,-2)$
$(1,2)$
$(2,1)$
Solution
Since, $l, m, n$ are in AP.
$
\therefore \quad 2 m=l+n
$
Given equation of line is
$
l x+m y+n=0
$
Now, assume that the point $(1,-2)$ satisfy the given equation.
$
\begin{array}{lrr}
\therefore & l-2 m+n=0 \\
\Rightarrow & 2 m=l+n \\
\Rightarrow & l, m, n \text { are in AP. }
\end{array}
$
Hence, option (2) is correct