Кощей старше Бабы Яги на возраст Ивана, следовательно, Ивану было 0 лет, т. е. новорожденный.
пример:
100=80+20, следовательно
99-79-19
98-78-18
97-77-17
96-76-16 и т.д.
Ответ:
1) (7/15-1/6) + 2/5 = 14/30-5/30+12/30=21/30=7/10
2)(3/8-1/9)+25/36 = 27/72-8/72+50/72=69/72
3)(8/9-5/6)+2/3 = 48/54-45/54+36/54=39/54
4)(7/8-13/20) + 9/10 = 35/40-26/40+36/40=45/40=1. 5/40= 1. 1/8
5)(7/18-1/12)+5/6 = 14/36-3/36+30/36=41/36=1. 5/36
6)(3/4-8/15)+17/20 =45/60-32/60+51/60=64/60=1. 4/60=1. 1/15
![y= \int {(sin2x-6cos^2x*sinx)} \, dx = \int {sin2x} \, dx -\int {6cos^2x*sinx} \, dx = \\ = \frac{1}{2} \int {sin2x} \, d2x +6\int {cos^2x} \, dcosx = -\frac{1}{2} cos2x+6* \frac{1}{3}cos^3x+C = \\ =2cos^3x- \frac{1}{2} cos2x+C](https://tex.z-dn.net/?f=y%3D+%5Cint+%7B%28sin2x-6cos%5E2x%2Asinx%29%7D+%5C%2C+dx+%3D+%5Cint+%7Bsin2x%7D+%5C%2C+dx++-%5Cint+%7B6cos%5E2x%2Asinx%7D+%5C%2C+dx+%3D+%5C%5C+%3D+%5Cfrac%7B1%7D%7B2%7D++%5Cint+%7Bsin2x%7D+%5C%2C+d2x++%2B6%5Cint+%7Bcos%5E2x%7D+%5C%2C+dcosx+%3D+-%5Cfrac%7B1%7D%7B2%7D+cos2x%2B6%2A+%5Cfrac%7B1%7D%7B3%7Dcos%5E3x%2BC+%3D+%5C%5C+%3D2cos%5E3x-+%5Cfrac%7B1%7D%7B2%7D+cos2x%2BC)
y(π/2)=2cos³(π/2) -(1/2)cosπ +C
2cos³(π/2) -(1/2)cosπ +C=3/2
0+1/2+C=3/2
C=1
y=2cos³x -(1/2)cos2x +1