Question

9. Solve the following system of equations. x + 2y − 6 = z 3y − 2z = 7 4 + 3x = 2y − 5z A. x = 0, y = 5, z = 4 B. C. D. x = 2, y = 1, z = 2

Answer 1

X + 2y - 6 = z..........x + 2y - z = 6
3y - 2z = 7
4 + 3x = 2y - 5z.....3x - 2y + 5z = -4

x + 2y - z = 6.....multiply by -3
3x - 2y + 5z = -4
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-3x - 6y + 3z = -18 (result of multiplying by -3)
3x - 2y + 5z = -4
--------------------add
-8y + 8z = - 22

-8y + 8z = -22
3y - 2z = 7 .....multiply by 4
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-8y + 8z = -22
12y - 8z = 28 (result of multiplying by 4)
----------------add
4y = 6
y = 6/4 reduces to 3/2

-8y + 8z = -22
-8(3/2) + 8z = -22
-12 + 8z = -22
8z = -22 + 12
8z = -10
z = -10/8 reduces to -5/4

x + 2y - 6 = z
x + 2(3/2) - 6 = -5/4
x + 3 - 6 = -5/4
x - 3 = -5/4
x = -5/4 + 3
x = -5/4 + 12/4
x = 7/4

solution is (7/4, 3/2, -5/4).....x = 7/4, y = 3/2, and z = -5/4