Abel’s Theorem Theorem 2 (Abel). If y 1, y 2 are twice continuously di erentiable solutions of y00+ a 1 (t)y0+ a 0 (t)y = 0; (1) where a 1, a 0 are continuous on I ˆR, then the Wronskian W 12 satis es W0 12 + a 1 (t)W 12 = 0: Therefore, for any t 0 2I, the Wronskian W 12 is given by the expression W 12 (t) = W 12 (t 0)e A1(t); where A 1 (t ...