It is known that y = y1-y2, Y1 and X are in positive proportion, Y2 and X2 are in inverse proportion, and when x = 1, y = - 14; when x = 4, y = 3. Find: (1) the functional relationship between Y and X; (2) the value range of independent variable x; (3) the value of y when x = 14

It is known that y = y1-y2, Y1 and X are in positive proportion, Y2 and X2 are in inverse proportion, and when x = 1, y = - 14; when x = 4, y = 3. Find: (1) the functional relationship between Y and X; (2) the value range of independent variable x; (3) the value of y when x = 14

(1) ∵ Y1 is positively proportional to x, Y2 is inversely proportional to x2 ∵ Y1 = XK1, y2 = k2x2, ∵ y = y1-y2, ∵ y = k1x-k2x2, ∵ (1, - 14), (4,3) is suitable for y = k1x-k2x2, ∵ - 14 = k1-k2, 3 = 2k1-k216, the solution is K1 = 2, K2 = 16. ∵ y = 2x-16x2. (2) the range of independent variable x is x > 0. (3) when x = 14, y = 214-162 = - 255