Question

тема: система рівнянь
способи додавання
2x-5y=9
5x+y=9

Answer 1

Объяснение:
$\left \{ {{2x-5y=9} \atop {5x+y=9}} \right.$
$\left \{ {{2x-5y=9} |*(-3) \atop {y=9-5x}} \right.$

$\left \{ {{-6+15(9-5x)=-27} \atop {y=9-5x}} \right.$
$\left \{ {{-6+135-75x=-27} \atop {y=9-5x}} \right.$
$\left \{ {{129-75x+27=0} \atop {y=9-5x}} \right.$
$\left \{ {{156-75x=0} \atop {y=9-5x}} \right.$
$\left \{ {{75x=156} \atop {y=9-5x}} \right.$

$\left \{ {{x=2\frac{6}{75 } \atop {y=9-5*2\frac{6}{75} }} \right.$
$\left \{ {{x=2\frac{6}{75 } \atop {y=9-5*\frac{156}{75} }} \right.$
$\left \{ {{x=2\frac{6}{75 } \atop {y=9-\frac{156}{15} }} \right.$
$\left \{ {{x=2\frac{6}{75 } \atop {y=9-\frac{52}{5} }} \right.$
$\left \{ {{x=2\frac{6}{75 } \atop {y=-\frac{7}{5} }} \right.$

$\left \{ {{x=2\frac{6}{75 } \atop {y=-1\frac{2}{5} }} \right.$