Question 1147938
<br>
The graphs of Ax+By=M and Cx+Dy=N are parallel if, and only if,<br>
A/B = C/D<br>
or, alternatively,<br>
A/C = B/D<br>
Using the first ratio, we have<br>
{{{k/2 = 18/k}}}
{{{k^2 = 36}}}
{{{k = 6}}}  OR  {{{k = -6}}}<br>
Of course we choose k=6 for the answer, because the question asks for a positive value.