Hi, I was just wondering if : (y^2 - 1)*dx/dy + x = 0 In this case, x is the dependent variable. Is linear? I know it is but I want to understand why. My question is with the coefficients. The first coefficient has a y to the power of 2 to it and a constant. It is also a function of y (independent var in this case) for obvious reasons. I'm wondering if the power in the coefficient matters ? For example , instead of getting (y^2 - 1) as a coeff. , would simply y^5 as the coefficient still make the eq. linear? Also , for an equation to be non-linear , must the coefficients involve the dependent var. instead of the independent one? Thank you very much!