Question

Solve the following system of equations.
x + 3y - z = 2
x - 2y + 3z = 7
x + 2y - 5z = -21

Answer 1

does it have to be solved a certain way ? substitution, elimination, matrix, or can you solve it any way you choose ?

Answer 2

Like the answer choices are
(2, 3, 5)

(-2, 3, 5)

(2, -3, 5)

(2, 3, -5)

Answer 3

do you have a graphing calculator?..

Answer 4

x + 3y - z = 2 --->(-1)
x - 2y + 3z = 7
---------------
-x - 3y + z = -2 (result of multiplying by -1)
x - 2y + 3z = 7
---------------add
-5y + 4z = 5

x - 2y + 3z = 7 --->(-1)
x + 2y - 5z = -21
---------------
-x + 2y - 3z = -7 (result of multiplying by -1)
x + 2y - 5z = -21
---------------add
4y - 8z = - 28

-5y + 4z = 5 --->(2)
4y - 8z = -28
--------------
-10y + 8z = 10 (result of multiplying by 2)
4y - 8z = -28
-------------add
-6y = -18
y = -18/-6
y = 3

4y - 8z = -28
4(3) - 8z = -28
12 - 8z = -28
-8z = -28 - 12
-8z = - 40
z = -40/-8
z = 5

x + 3y - z = 2
x + 3(3) - 5 = 2
x + 9 - 5 = 2
x + 4 = 2
x = 2 - 4
x = -2

solution is : (-2,3,5)