3. y=sin3x-sinx
y(-x)=-sin(-x)-sin(3(-x))=-(-sin(x)+sin(3x))=-y(x) => нечётная
![\left \{ {{x-2y=0} \atop {5xy+y^2=44}} \right. \left \{ {{x=2y} \atop {5xy+y^2=44}} \right.](https://tex.z-dn.net/?f=%5Cleft+%5C%7B+%7B%7Bx-2y%3D0%7D+%5Catop+%7B5xy%2By%5E2%3D44%7D%7D+%5Cright.+%5Cleft+%5C%7B+%7B%7Bx%3D2y%7D+%5Catop+%7B5xy%2By%5E2%3D44%7D%7D+%5Cright.)
Подставим первое уравнение во второе и отдельно его решим
![5(2y)y+y^2=44 \\ 10y^2+y^2=44 \\ 11y^2=44|:11 \\ y^2=4 \\ y=\sqrt{4} \\ y=+-2](https://tex.z-dn.net/?f=5%282y%29y%2By%5E2%3D44+%5C%5C+10y%5E2%2By%5E2%3D44+%5C%5C+11y%5E2%3D44%7C%3A11+%5C%5C+y%5E2%3D4+%5C%5C+y%3D%5Csqrt%7B4%7D+%5C%5C+y%3D%2B-2+)
Вернемся в систему которых теперь будет две
![1. \left \{ {{x=2y} \atop {y=2}} \right. \left \{ {{x=2*2} \atop {y=2}} \right. \left \{ {{x=4} \atop {y=2}} \right. \\2. \left \{ {{x=2y} \atop {y=-2}} \right. \left \{ {{x=2*(-2)} \atop {y=-2}} \right. \left \{ {{x=-4} \atop {y=-2}} \right.](https://tex.z-dn.net/?f=1.+%5Cleft+%5C%7B+%7B%7Bx%3D2y%7D+%5Catop+%7By%3D2%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%3D2%2A2%7D+%5Catop+%7By%3D2%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%3D4%7D+%5Catop+%7By%3D2%7D%7D+%5Cright.+%5C%5C2.+%5Cleft+%5C%7B+%7B%7Bx%3D2y%7D+%5Catop+%7By%3D-2%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%3D2%2A%28-2%29%7D+%5Catop+%7By%3D-2%7D%7D+%5Cright.++%5Cleft+%5C%7B+%7B%7Bx%3D-4%7D+%5Catop+%7By%3D-2%7D%7D+%5Cright.+)
Ответ(4:2) и (-4:-2)
Log2(20-18x)=log2(18-20x)+log2(2)
log2(20-18x)=log2((18-20x)*2)
log2(20-18x)=log2(36-40x)
т.к. основания одинаковые, то
20-18x = 36-40x
40x-18x=36-20
22x=16
x=16/22
x=8/11
А^2б^3-а^3б^4=а^2б^3(1-аб)
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(a^2+ab-a^2-b^2+2ab)/(a^2-b^2)=(3ab-b^2)/(a^2-b^2)