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