Question

Resolva os Sistemas
A) {-2X-6Y=6
{X+7Y= -3


B) {5X-Y=1
{2X-3Y=-10


C) {X+8Y=-14
{2X-9Y=-3

Answer 1

A)
-2X - 6Y = 6  (:2)
X + 7Y = -3 

- x - 3y = 3
 x + 7y = - 3   (+)
---------------------
     4y = 0
y = 0/4
y = 0

x + 7y = - 3
x + 7.0 = - 3
x = - 3

***************************
B)
5X - Y = 1           (-3)
2X - 3Y = - 10

- 15x + 3y = - 3
  2x - 3y = - 10   (+)
---------------------------------
  - 13x = - 13 (-1)
   13x = 13
    x = 13/13
     x = 1

5x - y = 1
5.1 - y = 1
5 - y = 1
5 - 1 = y
4 = y
y = 4

***********************
C)
X + 8Y = - 14    (-2)
2X - 9Y = - 3  

- 2x - 16y = 28
  2x - 9y = - 3
-------------------------
       - 25y = 25  (-1)
     25y = - 25
      y = - 25/25
   y = - 1

x + 8y = - 14
x + 8.(-1) = - 14
x - 8 = - 14
x = - 14 + 8
x = - 6