Смотри фотографию, надеюсь поймёшь
X+8,x
s=
![\frac{ a_{1} }{1-q}](https://tex.z-dn.net/?f=+%5Cfrac%7B+a_%7B1%7D+%7D%7B1-q%7D+)
a₁≡x+8 - ?
q=x/(x+8)
![\frac{ x+8{} }{1- \frac{x}{x+8} } =18](https://tex.z-dn.net/?f=+%5Cfrac%7B+x%2B8%7B%7D+%7D%7B1-+%5Cfrac%7Bx%7D%7Bx%2B8%7D+%7D+%3D18)
![\frac{x+8}{ \frac{x+8-x}{x+8} } = \frac{(x+8) ^{2} }{8}](https://tex.z-dn.net/?f=+%5Cfrac%7Bx%2B8%7D%7B+%5Cfrac%7Bx%2B8-x%7D%7Bx%2B8%7D+%7D+%3D+%5Cfrac%7B%28x%2B8%29+%5E%7B2%7D+%7D%7B8%7D+)
![\frac{ x^{2}+16x+64 }{8} =18](https://tex.z-dn.net/?f=+%5Cfrac%7B+x%5E%7B2%7D%2B16x%2B64+%7D%7B8%7D+%3D18)
x²+16x+64=144
x²+16x-80=0
D=64+80=144
x₁=-8+12=4, x₂=-8-12=-20⇒
x+8=4+8=12, x+8==-20+8=-12⇒a₁=12, a₁=-12
3х-5х/8-х=6/2+15/4-1+3
2х-5х/8=8целых 3/4
11х/8=8целых 3/4
11х/8=27/4
11х=54
х=4целых 5/27