Question

Himpunan penyelesaian sistem persamaan 2x-3/3 - y-4/4=2 1/2 dan x+4/2 - 2y-3/4=5 1/4 adalah...

Answer 1

4(2x-3)/12 - 3(y-4)/12 = 30/12
8x-12-3y+12=30
8x-3y=30......(1)

2(x+4)/4 - 2y-3/4 = 21/4
2x+8-2y+3=21
2x-2y=10
x-y=5 ➡ x+5=y....(2)

8x-3(x-5)=30
8x-3x+15=30
5x=15
x=3

y=x-5
y=3-5=-2

Answer 2

(2x-3) / 3 - (y-4)/4 = 2  1/2             ....> dikali 12
(x+4)/2 - (2y-3) / 4 = 5  1/4          ,......> dikali 4

menjadi :
4(2x-3) - 3(y-4) = 30    > 8x - 12 - 3y + 12 = 30    ...> 8x-3y = 30
2(x+4) - (2y-3) = 21     > 2x +  8 - 2y +  3 =  21       ...> 2x-2y = 10

eliminasi persamaan :
8x-3y = 30
2x-2y = 10   ......>dikali 4,
menjadi 
8x - 8y = 40
8x - 3y = 30   -
      -5y  = 10
          y = -2
subtitusi nilai y :
2x-2y = 10
2x - 2 (-2) = 10
2x + 4 = 10
2x  = 6
  x = 3