Question
If the line $$2x + y = k$$ passes through the point which divides the line segment joining the points (1, 1) and (2, 4) in the ratio 3 : 2, then $$k$$ equals :
A.
$$\frac{{29}}{5}$$
B.
5
C.
6
D.
$$\frac{{11}}{5}$$
Answer :
6
Solution :
Let the joining points be $$A\left( {1,\,1} \right)$$ and $$B\left( {2,\,4} \right)$$
Let point $$C$$ divides line $$AB$$ in the ratio 3 : 2
So, by section formula we have
$$C = \left( {\frac{{3 \times 2 + 2 \times 1}}{{3 + 2}},\,\frac{{3 \times 4 + 2 \times 1}}{{3 + 2}}} \right) = \left( {\frac{8}{5},\,\frac{{14}}{5}} \right)$$
Since Line $$2x + y = k$$ passes through $$C\left( {\frac{8}{5},\,\frac{{14}}{5}} \right)$$
$$\therefore \,\,C$$ satisfies the equation $$2x + y=k$$
$$ \Rightarrow \frac{{2 + 8}}{5} + \frac{{14}}{5} = k\,\,\,\,\, \Rightarrow k = 6$$