WEBVTT 00:00:00.000 --> 00:00:05.000 Most solvers available on the market do not accept the differential equation in this form-- 00:00:05.000 --> 00:00:09.000 the second-order differential equation, which is not an explicit form. 00:00:09.000 --> 00:00:16.000 What you instead have to provide is a function that returns the first derivative, the rate of change. 00:00:16.000 --> 00:00:22.000 The trick is to turn this differential equation into two differential equations of first order. 00:00:22.000 --> 00:00:28.000 Here is a hint for you--the first equation should be that the derivative of x with respect to time 00:00:28.000 --> 00:00:34.000 is some new variable called y, and now you have to provide the second equation 00:00:34.000 --> 00:00:36.000 for the derivative of y with respect to time. 00:00:36.000 --> 00:00:44.000 Should that be 7-3y+4x or 7-3 times the derivative of x plus 4x 00:00:44.000 --> 99:59:59.999 or 1/37 minus the second derivative plus 4x or 1/37 minus the first derivative of y plus 4x.