{ x + y = a − 3 x − y = 3 a − 5 {\displaystyle {\begin{cases}x+y=a-3\\x-y=3a-5\\\end{cases}}}
2 x = a − 3 + 3 a − 5 2 x = 4 a − 8 x = 2 a − 4 {\displaystyle {\begin{aligned}&2x=a-3+3a-5\\&2x=4a-8\\&x=2a-4\\\end{aligned}}}
נציב את X במשוואה הראשונה : x + y = a − 3 2 a − 4 + y = a − 3 y = − a + 1 {\displaystyle {\begin{aligned}&x+y=a-3\\&2a-4+y=a-3\\&y=-a+1\\\end{aligned}}}
| 2 a − 4 | < 10 − 10 < 2 a − 4 > 10 {\displaystyle {\begin{aligned}&|2a-4|<10\\&-10<2a-4>10\end{aligned}}}
2 a − 4 < 10 2 a < 14 a < 7 {\displaystyle {\begin{aligned}&2a-4<10\\&2a<14\\&a<7\\\end{aligned}}}
− 3 < x < 7 {\displaystyle {\begin{aligned}-3<x<7\end{aligned}}}
| − a + 1 | > 3 {\displaystyle {\begin{aligned}&|-a+1|>3\\\end{aligned}}}
− a + 1 < − 3 − a < − 4 a > 4 {\displaystyle {\begin{aligned}&-a+1<-3\\&-a<-4\\&a>4\\\end{aligned}}}
x < − 2 ; x > 4 {\displaystyle {\begin{aligned}x<-2;x>4\end{aligned}}}
x < − 2 x > 4 − 3 < x < 7 {\displaystyle {\begin{aligned}&x<-2\\&x>4\\&-3<x<7\end{aligned}}}
