The following direction field corresponds to which of the fo
     The following direction field corresponds to which of the following differential equations? Select only ONE answer.  y\' = sin (3 x)  y\' = 3x / y  y\' =3xy  y\' = 3y 
  
  Solution
The problem can be solved only by checking the choices with the figure (and some intuition)
 follow these steps :-
1)first we note that along x axis line is horizontal and the slope is zero. therefore when x =0, y\' = 0. Therefore fourth option is not possible
2)we note that the plot is symmetric along x axis. and it varies with the value of y. therefore the slope expression should depend on y.
3) we can see that when y tends to infinity, line becomes vertical i.e slope tends to infinity and when y tends to zero, slope tends to zero. therefore clearly the only option possible is the second one.
Therefore the answer is 3x/y

