Question

x - y = 10.
a) {
2x + 3 =10

Answer 1

Resposta:

a) x = 8 e y = -2

b) x = 1 e y = 5

Explicação passo a passo:

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

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

   $\left \{ {{-2x+2y=-20} \atop {2x+3y=10}} \right.$

   $\left \{ {{2y=-20} \atop {3y=10}} \right.$

    5y = -10

      y = $\frac{-10}{5}$

      y = -2

     x - y = 10

     x - (-2) = 10

     x + 2 = 10

     x = 10 - 2

    x = 8

-------------------------------------------------------------------------------------------------------------

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

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

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

   $\left \{ {{4x=14} \atop {5x=-5}} \right.$

    9x = 9

      x = $\frac{9}{9}$

      x = 1

     

    2x + y = 7

    2.(1) + y = 7

    2 + y = 7

    y = 7 - 2

    y = 5