diketahui sistem persamaan 3x -2y = 14 dan 5x + 4y = 5, maka nilai x + 4y adalah.....

3x-2y=14...(1) => 6x-4y=28...(3)
5x+4y=5....(2)

6x-4y=28
5x+4y=5
--------------- -
11x=33
x = 3
3x-2y=14
-2y= 14-3•3
= 14-9
y=5/-2= -5/2

x+4y= 3+4•(-5/2)
=3+-10
=-7

3x - 2y = 14   |x2 | = 6x - 4y = 28 }
5x + 4y = 5    |x1 | = 5x + 4y = 5  }
(6x-4y) + (5x + 4y) = 28 + 5
 11x = 33   - >  x = 33/11 = 3
5(3)+4y = 5
15 + 4y = 5
 4y = 5 - 15 = -10
 x+ 4y = 3 + (-10) = -7