Let y1 and y2 be two solutions of A(x)y" + B(c)y' + C(x)y = 0 on a open interval I where A, B, and C are continuous and A (a ) is never zero. dw 1. Let W = W (y1, y2 ). Show that A(a) dx = (y1) (Ay'2) - (y2) (Ay';). Then substitute for dw Ay', and Ay' from the original equation to show that A(ac) = -B(ac ) W (ac). dx 2. Solve this first-order equation to deduce Abel's formula W (x) = K exp (- B(ac) dx A(a) Where K is a constant. 3. Why does the Abel's formula imply that the Wronskian W (y1, y2 ) is either zero everywhere or nonzero everywhere?