Question

Завершите решение.
$\left \{ {{4x+5y=23} \atop {x+2y=8}} \right. =\ \textgreater \ \left \{ {{y=}\frac{23-4x}{5} \atop {x+2y=8}} \right.$

Answer 1

$\left \{ {{4x+5y=23} \atop {x+2y=8}} \right. =>  \left \{ {{4x+5y=23} \atop {4x+8y=32}} \right. \\(4x+5y)-(4x+8y)=23-32\\-3y=-9 => y=3\\x+2y=8 => x+6=8 => x=2$

$\left \{ {{4x+5y=23} \atop {x+2y=8}} \right. =>\left \{ {{y=}\frac{23-4x}{5}  \atop {x+2y=8}} \right. \\x+2*(\frac{23-4x}{5} )=8\\5x+46-8x=40\\-3x=-6\\x=2\\2+2y=8\\2y=6\\y=3$

Ответ: (2;3)

Answer 2

$4x + 5y = 23 \\ x + 2y = 8 \\ \\ y = \frac{23 - 4x}{5} \\ x + 2y = 8 \\ \\ x + \frac{2(23 - 4x)}{5} = 8 \: ( \times 5) \\ 5x + 2(23 - 4x) = 40 \\5x + 46 - 8x = 40 \\ - 3x = - 6 \\ x = 2 \\ \\ 2 + 2y = 8 \\ 2y = 6 \\ y = 3$
Ответ: (2;3)