Let \( P \) be a plane \( l x+m y+n z=0 \) containing the line, \( \frac{1-x}{1}=\frac{y+4}{2}=\frac{z+2}{3} \) . If pane \( P \) divides the line segments \( A B \) joining pionts \( A(-3,-6,1) \) and \( B(2,4,-3) \) in ratio \( k: 1 \) then the value of \( k \) is equal to :