Problem: x = number of rabbits y = number of foxes Accept the usual assumptions involved in predator-prey (Lotka-Volterra) problems. dx/dt = 0.04x - 0.002xy dy/dt = -0.08y + 0.0004xy Initial conditions: 200 rabbits and 10 foxes This problem is in a textbook. A graph of the functions x and y when 0 </= t </= 240 is illustrated without showing the functions that are graphed. I am trying to generate those functions. I am having trouble solving the differential equations. I began by separating variables... dx/dt = 0.04x - 0.002xy 500(1/x)dx = (20 - y)dt 500 ln(x) = t(20 - y) + C1 Using initial conditions, C1 = 500 ln(200), so 500 ln(x) = t(20 - y) + 500 ln(200) Solving the other equation in a similar way gives 2500 ln(y) = t(x - 200) + 2500 ln(10) From here I tried several techniques put found myself painted into a corner. I am thinking I need to rethink the method of solving the equations above. Euler's Method may work to approximate values, but I don't know how to set it up. Suggestions? Thanks for taking a look.