Question

!resolva os sistemas de equações:!

a) 3x+y=9 b)x - 3y =1 c)2x +y -z= -1
2x+3y=13 2x + 5y=13 3y+2z=-5
7z=14

Answer 1

a.

$\left \{ {{2x + y = 9} \atop {2x + 3y = 13}} \right.$

(I) -(II)

2x -2x +y -3y = 9 -13

-2y = -4

y = 2

2x = 9 -2

x = 7/2

{7/2 , 2}

b.

$\left \{ {{x -3y = 1} \atop {2x + 5y = 13}} \right.$

-2(I) + (II)

2x -2x +5y -2(-3y) = 13 -2

-y = -11

y = 11

x = 1 +3*11

x = 34

{11 , 34}

c.

z = 2

3y = -5 -2*2

y = -3

2x -3 -2 = -1

2x = -1 + 5

x = 2

{2 , -3 , 2}