x^2-7x+q=0
по теореме виета:
![\left \{ {{x_{1}+x_{2}=7} \atop {x_{1}*x_{2}=q}} \right.](https://tex.z-dn.net/?f=%5Cleft+%5C%7B+%7B%7Bx_%7B1%7D%2Bx_%7B2%7D%3D7%7D+%5Catop+%7Bx_%7B1%7D%2Ax_%7B2%7D%3Dq%7D%7D+%5Cright.)
и по условию ![x_{1}=2,5x_{2}](https://tex.z-dn.net/?f=x_%7B1%7D%3D2%2C5x_%7B2%7D)
из первого уравнения системы находим ![x_{1}=7-x_{2}](https://tex.z-dn.net/?f=x_%7B1%7D%3D7-x_%7B2%7D)
и приравниваем к ![x_{1}=2,5x_{2}](https://tex.z-dn.net/?f=x_%7B1%7D%3D2%2C5x_%7B2%7D)
получаем, что
, ![x_{1}=2*2,5=5](https://tex.z-dn.net/?f=x_%7B1%7D%3D2%2A2%2C5%3D5)
подставляем в
и q=5*2=10
3)cos(-π)+ctg(-π/2)-sin(-3/2π)+ctg(-π/4)= -1+0 -1 -1=-3
4)3-sin^2(-π/3)-cos^2(-π/3)/2cos(-π/4)=3 -3/4-1/4/1=2
A) y = 32 + 12 = 44.
б) x = 2/14 = 1/7.
в) 15/x = 3/5;
x = .15/(3/5); x = 25.
г) 3x - 16 = x - 24;
3x - x = -24 + 16;
2x = -8;
x = -8/2
x = -4;
д) |5x| = 2;
x = +-0,5
<span>2sinx+sin2x=cosx+1</span>