1. The problem statement, all variables and given/known data Solve d^2x/dt^2 = (3x^3)/2 when dx/dt = -8 and x = 4 when t = 0 2. The attempt at a solution v = dx/dt dv/dx = d^2/dx^2 d^2x/dt^2 = v(dv/dx) = (3x^3)/2 v dv = (3x^3)/2 dx integrating and using limits and you get : v^2/2 -32 = (3x^4)/8 - 96 ............ 4v^2 = 3x^4 - 512 this is where I'm stuck I can take the square root of the 4v^2 but not the right hand side because of the three and the 512. I'm not sure if there is another technique I can use but finding the square root of both sides is the only way I was taught to do these problems and its the only example in the book. Any help would be appreciated.