Question

15х+11у-57=0 и 5х-у+17=0

Answer 1

$<var>\left \{ {{15x+11y-57=0} \atop {5x-y+17=0}} \right.\\ \\ \left \{ {{15x+11y=57} \atop {y=5x+17}} \right.\\ \\ 15x+11(5x+17)=57\\ 15x+55x+187=57\\ 70x=57-187\\ 70x=-130\\ x=-\frac{13}{7}\\ \\ y=5*(-\frac{13}{7})+17=-9\frac{2}{7}+17=7\frac{5}{7}</var>$