<span>12/19 * (1 7/12 * 4 13/21) =
12/19 *(19/12 * 4 13/21) =
(12/19*19/12) * 4 13/21 =
1 * 4 13/21 = 4 13/21,
(3 2/7 * 25,8) * 7/23 =
(23/7 * 25,8) * 7/23 =
(23/7 * 7/23) * 25,8 =
1 * 25,8 = 25,8</span>
= -xy^2+4xy..................................................
Всё очевидно!
3*sin2x - cos2x = 0 / Cos2x
3*tg2x - 1 = 0
3*tg2x = 1
tg2x = 1/3
2x = arctg(1/3) + pi*n
x = arctg(1/6) + pi*n / 2
как то так)))