Ответ:
1) 2х+3(5х+2)-23=0
2х+15х+6-23=0
17х-17=0
17(х-1)=0
х-1=0
х=1
у=5+2=7
2)у=х-1
2х+3(х-1)=7
2х+3х-3-7=0
5х-10=0
5(х-2)=0
х-2=0
х=2
у=2-1=1
3)х=17+10у
3(17+10у)+7у-23=0
51+30у+7у-23=0
37у+28=0
у= -28/37
х= 17+10(-28/37)=17 -280/37=349/37=9 16/37
4)у=7+ 9х/5
5х/2-6(9х/5)-5/10=0
5х/2-54х/5-5/10=0 |10
25х-108х-5=0
-83х=5
х= - 5/83
у= 7+(9(-5/83)÷5)= 7-9/83=572/83=6 74/83