... into two equations on separate domains.y 1 − y 1 = 0, y 1 (0) = 1, for x < 1 y2− y2= 1, y2 (1) = y 1 (1) , for x > 1 797 • y+ 3xy+ 2y = x2• y= yyThe degree ... doubles everyhour. For the continuous problem, we assume that this i s true for y(t). We write this as an equation:y(t) = αy(t).775 1 2 3 448 12 16 1 2 3 448 12 16 Figure 14 .1: The p opulation ... =y(x)x.P (1, u) + Q (1, u)u + xdudx= 0This equation is separable.P (1, u) + uQ (1, u) + xQ (1, u)dudx= 0 1 x+Q (1, u)P (1, u) + uQ (1, u)dudx= 0ln |x| + 1 u + P (1, u)/Q (1, u)du...