Question

РЕШИТЕ НАДО СРОЧНО!!!

Answer 1

1)
$\left \{ {{x=8+5y} \atop {2x+4y=30}} \right.$ ⇒ $\left \{ {{x=8+5y} \atop 2(8+5y +4y=30)}} \right.$ ⇒ $\left \{ {{x=8+5y} \atop {16+10y+4y=30}} \right.$ ⇒ $\left \{ {{x=8+5y} \atop {14y=14}} \right.$⇒$\left \{ {{x=8+5y} \atop {y=1}} \right.$ ⇒$\left \{ {{x=8+5} \atop {y=1}} \right.$ ⇒$\left \{ {{x=13} \atop {y=1}} \right.$
2)
$\left \{ {{y=2x-1} \atop {7x-6y=-4}} \right.$ ⇒$\left \{ {{y=2x-1} \atop {7x-6(2x-)=-4}} \right.$ ⇒ $\left \{ {{y=2x-1} \atop {7x-12x+6+4=0}} \right.$⇒
$\left \{ {{y=2x-1} \atop {-5x+10=0}} \right.$⇒$\left \{ {{y=2x-1} \atop {x=2}} \right.$⇒$\left \{ {{y=3} \atop {x=2}} \right.$
3)
$\left \{ {{5a-3(10-2a)=14} \atop {b=10-2a}} \right.$⇒$\left \{ {{5a-30+6a=14} \atop {b=10-2a}} \right.$⇒$\left \{ {{11a=44} \atop {b=10-2a}} \right.$⇒$\left \{ {{a=4} \atop {b=2}} \right.$