Сравните с нулем значение данных выражений (y-3)(y-5), (3-y)(y-5), (5-y)(3-y), если...

А) y<3, тогда y-3<0, y-5<0 (y-3)(y-5)>0

3-y>0, y-5<0 (3-y)(y-5)<0 
5-y>0, 3-y>0
(5-y)(3-y)>0

б) у>5
y-3>0, y-5>0
(y-3)(y-5)>0

3-y<0, y-5>0
(3-y)(y-5)<0 
5-y<0, 3-y<0 (5-y)(3-y)>0

в) 3 y-3>0, y-5<0 (y-3)(y-5)<0 
3-y<0, y-5<0 (3-y)(y-5)>0

5-y>0, 3-y<0 (5-y)(3-y)<0