Question

даю 15 баллов за все

Answer 1

1) $\left \{ {{x+y=3} \atop {x-y=7}} \right.$

$\left \{ {{x+y=3} \atop {x=y+7}} \right.$

$\left \{ {{y+7 +y=3} \atop {x=y+7}} \right.$

$\left \{ {{2y= -4} \atop {x=y+7}} \right.$

$\left \{ {{y=-2} \atop {x=y+7}} \right.$

$\left \{ {{y=-2} \atop {x=-2+7}} \right.$

$\left \{ {{y=-2} \atop {x=5}} \right.$

2)$\left \{ {{5x-6y=7} \atop {10x+6y=8}} \right.$

$\left \{ {{5x - 6y = 7} \atop { 6y=8-10x}} \right.$

$\left \{ {{5x-(8-10x)=7} \atop {6y=8-10x}} \right.$

$\left \{ {{x=1} \atop {6y=8-10*1}} \right.$

$\left \{ {{x=1} \atop {y=-\frac{1}{3} }} \right.$

3) $\left \{ {{5x+4y=25} \atop {5x-3y=-3}} \right.$

$\left \{ {{5x+4y=25} \atop {5x=-3+3y}} \right.$

$\left \{ {{-3+3y+4y=25} \atop {5x=-3+3y}} \right.$

$\left \{ {{y=4} \atop {5x=-3+3y}} \right.$

$\left \{ {{y=4} \atop {x=\frac{9}{5} }} \right.$

4)$\left \{ {{y=4-3x} \atop {5x-2y=14}} \right.$

$\left \{ {{y=4-3x} \atop {5x-2(4-3x) = 14}} \right.$

$\left \{ {{y=4-3x} \atop {x=2}} \right.$

$\left \{ {{y=4-3*2} \atop {x=2}} \right.$

$\left \{ {{y=-2} \atop {x=2}} \right.$

Answer 2

Ответ:

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