Question

Решите систему уравнений:
1) 7y-5x+18=0
5y+3x=20
2) 5y-6x+22=0
2y+x=15

Answer 1

1)
$\left \{ {{7y-5x+18=0} \atop {5y+3x=20}} \right. \\ \left \{ {{21y-15x=-54} \atop {25y+15x=100}} \right. \\ \left \{ {{21y-15x=-54} \atop {46y=46}} \right. \\ \left \{ {{21y-15x=-54} \atop {y=1}} \right. \\ \left \{ {{21-15x=-54} \atop {y=1}} \right. \\ \left \{ {{-15x=-75} \atop {y=1}} \right. \\ \left \{ {{x=5} \atop {y=1}} \right.$

2)
$\left \{ {{5y-6x+22=0} \atop {2y+x=15}} \right. \\ \left \{ {{5y-6x=-22} \atop {12y+6x=90}} \right. \\ \left \{ {{5y-6x=-22} \atop {17y=68}} \right. \\ \left \{ {{5y-6x=-22} \atop {y=4}} \right. \\ \left \{ {{20-6x=-22} \atop {y=4}} \right. \\ \left \{ {{-6x=-42} \atop {y=4}} \right. \\ \left \{ {{x=7} \atop {y=4}} \right.$