Question

Solve the following systems of equations:

x - y + z = 4

x - 2y + 3z = 9

2x + y + 3z = 1

Answer 1

x - y + z = 4

x - 2y + 3z = 9

2x + y + 3z = 1

Subtracting eq2 and eq3

⇒ x + 3y = 0

⇒ x = -3y

Substituting in eq1

⇒ -3y – y + z = 4

⇒ z = 4 + 4y

Substituting in eq2

⇒ -3y – 2y + 12 + 12y = 1

⇒ 7y = -11 ⇒ y = - 11/7

Thus,

x = 33/7

And z = 4 – 44/7 = - 16/7