21. A differential equation may possess more than one family of solutions. (a) Plot different members of the families y 1(x) x2 c1 and y 2(x) x2 c2. (b) Verify that y 1(x) and y 2(x) are two solutions of the nonlinear first-order differential equation (y)2 4x2 . (c) Construct a piecewise-defined function that is a solution of the nonlinear DE in part (b) but is not a member of either family of solutions in part (a). 2