Question

помогите пожалуйста решить​

Answer 1

Ответ:

А) $\left \{ {x=3} \atop {x+2y=9}} \right.$

$3+2y=9$

$y=3$

$(x , y )=(3,3)$

Проверка:

$\left \{ {{3=3} \atop {3+2*3=9}} \right.$

$\left \{ {{3=3} \atop {9=9}} \right.$

( x, y ) = ( 3, 3 )

Б) $\left \{ {{x-4y=5} \atop {y=0,5}} \right.$

$x-4*0,5=5$

$x=7$

$(x, y)=(7,0,5)$

Проверка:

$\left \{ {{7-4*0,5=5} \atop {0,5=0,5}} \right.$

$\left \{ {{5=5} \atop {0,5=0,5}} \right.$

( x, y ) = ( 7, 0,5 )

В) $\left \{ {{x=y} \atop {3x+2y=10}} \right.$

$3y+2y=10$

$y=2$

$x=2$

$(x,y)=(2,2)$

Проверка:

$\left \{ {{2=2} \atop {3*2+2*2=10}} \right.$

$\left \{ {{2=2} \atop {10=10}} \right.$

( x, y ) = ( 2, 2 )

Г) $\left \{ {{x=3y-1} \atop {x-2y=4}} \right.$

$3y-1-2y=4$

$y=5$

$x=3*5-1$

$x=14$

$(x,y)=(14,5)$

Проверка:

$\left \{ {{14=3*5-1} \atop {14-2*5=4}} \right.$

$\left \{ {{14=14} \atop {4=4}} \right.$

( x, y ) = ( 14, 5 )

Д)  $\left \{ {{3x+y=13} \atop {5x+4y=31}} \right.$

$5x+4(13-3x)=31$

$x=3$

$y=13-3*3$

$y=4$

$( x,y)=(3,4)$

$\left \{ {{3*3+4=13} \atop {5*3+4*4=31}} \right.$

$\left \{ {{13=13} \atop {31=31}} \right.$

( x, y ) = ( 3, 4 )