У=-8 1/7+5 1/7
<em>х=-3</em>
!!!!!!!!!!
2.
у(х)=х²+cosx
y(-x)=(-x)²+cos(-x)=x²+cosx
Так как у(х)=у(-х), то функция четная.
3.
Т=π
у=cos2x
y=cos2(x+π)=cos(2x+2π)=cos2x.
4/3Х +2/3 = 2Х -1
4Х + 2 = 3(2Х-1)
4Х +2 = 6Х -3
4Х -6Х = -3-2
-2Х = -5
2Х = 5
<u>Х = 2,5</u>
![x_1=-\frac{1}{5} \\ x_2=2](https://tex.z-dn.net/?f=x_1%3D-%5Cfrac%7B1%7D%7B5%7D+%5C%5C+x_2%3D2)
Стандартная квадратичная форма уравнения
ax²+bx+c=0
Теорема Виета:
![\left \{ {{x_1+x_2=-b} \atop {x_1*x_2=c}} \right.](https://tex.z-dn.net/?f=%5Cleft+%5C%7B+%7B%7Bx_1%2Bx_2%3D-b%7D+%5Catop+%7Bx_1%2Ax_2%3Dc%7D%7D+%5Cright.)
![\left \{ {{-\frac{1}{5}+2=-\frac{b}{a} } \atop {-\frac{1}{5}*2=\frac{c}{a}}} \right\\ \left \{ {{\frac{9}{5}=-\frac{b}{a} } \atop {-\frac{2}{5}=\frac{c}{a} }} \right\\](https://tex.z-dn.net/?f=%5Cleft+%5C%7B+%7B%7B-%5Cfrac%7B1%7D%7B5%7D%2B2%3D-%5Cfrac%7Bb%7D%7Ba%7D+%7D+%5Catop+%7B-%5Cfrac%7B1%7D%7B5%7D%2A2%3D%5Cfrac%7Bc%7D%7Ba%7D%7D%7D+%5Cright%5C%5C+%5Cleft+%5C%7B+%7B%7B%5Cfrac%7B9%7D%7B5%7D%3D-%5Cfrac%7Bb%7D%7Ba%7D+%7D+%5Catop+%7B-%5Cfrac%7B2%7D%7B5%7D%3D%5Cfrac%7Bc%7D%7Ba%7D+%7D%7D+%5Cright%5C%5C)
Пусть а=1, тогда
![b=-\frac{9}{5} \\ c=-\frac{2}{5}\\ \\ x^2-\frac{9}{5}x-\frac{2}{5}=0](https://tex.z-dn.net/?f=b%3D-%5Cfrac%7B9%7D%7B5%7D+%5C%5C+c%3D-%5Cfrac%7B2%7D%7B5%7D%5C%5C+%5C%5C+x%5E2-%5Cfrac%7B9%7D%7B5%7Dx-%5Cfrac%7B2%7D%7B5%7D%3D0)
умножим на 5, тогда
5х²-9х-2=0
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