Question

Resolva os sistemas abaixo

a) {4x+y=10
{8x+3y=10

b) {5x+4y=10
{X+2y=2

c) {5x+y=4
{X+6y=-5

Answer 1

a)
4x + y = 10     (-3)
8x + 3y = 10

- 12x - 3y = - 30
   8x + 3y = 10   (+)
--------------------------
 - 4x = - 20  (-1)
   4x = 20
x = 20/4
x = 5

4x + y = 10
4.5 + y = 10
20 + y = 10
y = 10 - 20
y = - 10

*******************************
b)
5x + 4y = 10
 x + 2y = 2       (-2)

  5x + 4y = 10
- 2x - 4y = - 4
-----------------------
  3x = 6
   x = 6/3
  x = 2

x + 2y = 2
2 + 2y = 2
2y = 2 - 2
2y = 0
y = 0/2
y = 0

c) 
5x + y = 4      
x + 6y = - 5     (-5)

5x + y = 4
- 5x - 30y = 25  (+)
---------------------------
    - 29y = 29 (-1)
      29y = - 29
      y = - 29/29
     y = - 1

5x + y = 4
5x - 1 = 4
5x = 4 + 1
5x = 5
x = 5/5
x = 1