Question

Решить с помощью {х+3у=7 {х-3у=25

Answer 1

$\left \{ {{x+3y=7} \atop {x-3y=25}} \right. \bigg{+}\\ \left \{ {{2x=32} \atop {3y=25-x}} \right.\\ \left \{ {{x=16} \atop {y=(25-16):3}} \right.\\ \left \{ {{x=16} \atop {y=3}} \right.$
решено методом сложения

Answer 2

2x=32
x=16
16+3y=7
y=-3
(x,y)=(16,-3)
$\left \{ {{16+3x*(-3)=7} \atop {16-3x*(-3)=25}} \right.$
$\left \{ {{7=7} \atop {25=25}} \right.$

ответ- (х,у)=(16,-3)