5а²+10а = 0
5а(а+2) = 0
5а = 0 а+2 = 0
а = 0 а = -2
( 3х - 15 ) - ( 9 + 6х ) = - 3х
3х - 15 - 9 - 6х = - 3х
- 3х - 24 = - 3х
- 24 = - 3х + 3х
- 24 не равен 0
Ответ нет решений
![\frac{1}{ctg (2x)-1}=0;\\ 1=0;](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bctg+%282x%29-1%7D%3D0%3B%5C%5C+1%3D0%3B)
решений нет
![\frac{1}{ctg (2x-1)}=0;\\ 1=0;](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bctg+%282x-1%29%7D%3D0%3B%5C%5C+1%3D0%3B)
решений нет
![\frac{1}{ctg (2x)}-1=0;\\ \frac{1}{ctg (2x)}=1;\\ ctg (2x)=\frac{1}{1};\\ ctg(2x)=1;\\ 2x=\frac{\pi}{4}+\pi*k;\\ x=\frac{\pi}{8}+\frac{\pi*k}{2}](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bctg+%282x%29%7D-1%3D0%3B%5C%5C+%5Cfrac%7B1%7D%7Bctg+%282x%29%7D%3D1%3B%5C%5C+ctg+%282x%29%3D%5Cfrac%7B1%7D%7B1%7D%3B%5C%5C+ctg%282x%29%3D1%3B%5C%5C+2x%3D%5Cfrac%7B%5Cpi%7D%7B4%7D%2B%5Cpi%2Ak%3B%5C%5C+x%3D%5Cfrac%7B%5Cpi%7D%7B8%7D%2B%5Cfrac%7B%5Cpi%2Ak%7D%7B2%7D)
k є Z
ответ: <var>
,k є Z</var>
13-4z>5-6z
Переносим знаки с Z в одну сторону, а просто числа в другую.
2z>-8
z>-4