Jawab:

a) 2x - y = -7   .... pers 1

    x - 3y = -11 .... pers 2

Eliminasi x pers 1 dan pers 2

   2x - y = -7     | ×1

    x - 3y = -11   | ×2

____________

 2x -   y  = -7

 2x - 6y = -22

____________ -

        5y = 15

          y = 15 / 5 = 3

Eliminasi y pers 1 dan pers 2

   2x - y = -7     | ×3

    x - 3y = -11   | ×1

____________

 6x - 3y  = -21

   x - 3y  = -11

____________ -

 5x         = -10

          x = -10 / 5 = -2

HP = { -2, 3 }

b) x + 6y = -1  .... pers 1

  2x - 3y = 13​ .... pers 2

Eliminasi x pers 1 dan pers 2

   x + 6y = -1     | ×2

  2x - 3y = 13   | ×1

____________

 2x + 12y  = -2

 2x -  3y  = 13

____________ -

        15y = -15

          y = -15 / 15 = -1

Eliminasi y pers 1 dan pers 2

   x + 6y = -1     | ×1

  2x - 3y = 13   | ×2

____________

   x + 6y = -1

  4x - 6y  = 26

____________ +

 5x         = 25

          x = 25 / 5 = 5

HP = { 5, -1 }