Question

regra de gramer x + y = 4 x - 3y = -4

Answer 1

x+y=4

x-3y=-4

d= 1   1      d=1.(-3)-1.1= -3-1=-4

    1    -3

dx=4      1    dx=4.(-3)-(-4.1)=-12+4=-8

     -4     -3

dy= 1    4    dy=1.(-4)-(4.1)=-4-4=-8

      1    -4

x=dx/d        y=dy/d

x=-8/-4        y=-8/-4

x=2             y=2

Answer 2

regra de Cramer

x + y = 4

x - 3y = -4

matriz A

1    1

1   -3

det(A) = -3 - 1 = -4

matriz Ax

4    1

-4  -3

det(Ax) = -12 + 4 = -8

matriz Ay

1     4

1   -4

det(Ay) = -4 - 4 = -8

agora

x = det(Ax)/det(A) = -8/-4 = 2

y = det(Ay)/det(A) = -8/-4 = 2