Question

решите систему линейных урвнений {y-5x=-21 {3x+y-11=0

Answer 1

$\left \{ {{y-5x=-21} \atop {3x+y-11=0}} \right. \left \{ {{-5x+y=-21} \atop {3x+y=11}} \right. \left \{ {{5x-y=21} \atop {3x+y=11}} \right. \\8x=32\\x=4\\y=-21+5*4\\y=-1$