Solve using the elimination method. Show your work. If the system has no solution or an infinite number of solutions, state this.
-7x + 5y = -56

-21x – 2y = -168

Question

Solve using the elimination method. Show your work. If the system has no solution or an infinite number of solutions, state this.
-7x + 5y = -56

-21x – 2y = -168

anonymous · Answer

-7x + 5y = -56    -------- (i)      multiply by -3 and add to (ii)

-21x – 2y = -168 -------- (ii)
  21x -15y = 168   and we get
          -17y = 0
so y = 0/-17   => y = 0

substitute y = 0 in (i)
-7x + 5(0) = -56
-7x = -56
x = -56/-7
x = 8

so the unique solution is (8, 0)