Question

Реши систему уравнений:
4x−5y=7
2x+10y=25

ответ: (...;...)

Answer 1

ответ на фото.............

Answer 2

$(3\frac{9}{10}; \quad 1\frac{18}{25})$

Объяснение:

$\left \{ {{4x-5y=7} \atop {2x+10y=25}} \right. \Leftrightarrow \left \{ {{4x-5y=7} \atop {2x \cdot (-2)+10y \cdot (-2)=25 \cdot (-2)}} \right. \Leftrightarrow \left \{ {{4x-5y=7} \atop {-4x-20y=-50}} \right. \Leftrightarrow$

$\Leftrightarrow \left \{ {{4x-5y=7} \atop {-4x+4x-20y+(-5y)=-50+7}} \right. \Leftrightarrow \left \{ {{4x-5y=7} \atop {-25y=-50+7}} \right. \Leftrightarrow \left \{ {{4x-5y=7} \atop {-25y=-43}} \right. \Leftrightarrow \left \{ {{4x-5y=7} \atop {y=\frac{43}{25}}} \right. \Leftrightarrow$

$\Leftrightarrow \left \{ {{4x-5 \cdot \frac{43}{25}=7} \atop {y=\frac{43}{25}}} \right. \Leftrightarrow \left \{ {{4x- \frac{43}{5}=7} \atop {y=\frac{43}{25}}} \right. \Leftrightarrow \left \{ {{4x=\frac{35}{5}+\frac{43}{5}} \atop {y=\frac{43}{25}}} \right. \Leftrightarrow \left \{ {{4x=\frac{78}{5}} \atop {y=\frac{43}{25}}} \right. \Leftrightarrow \left \{ {{x=\frac{78}{20}} \atop {y=\frac{43}{25}}} \right. \Leftrightarrow \left \{ {{x=\frac{39}{10}} \atop {y=\frac{43}{25}}} \right. \Leftrightarrow$

$\Leftrightarrow \left \{ {{x=3\frac{9}{10}} \atop {y=1\frac{18}{25}}} \right. ;$

$(3\frac{9}{10}; \quad 1\frac{18}{25});$