9.
Solve the following system of equations
3x −2y + 4z = 20
−x + 5x +12z = 73
x + 3y −2z = 1

Select the appropriate response:

A) x =4, y = 3, z = 5
B) x = 2, y = 3, z = 5
C) x = 5, y = 5, z = 5
D) x = 7, y =8, z = 5

B) x = 2, y = 3 and z = 5.

Step-by-step explanation:

3x −2y + 4z = 20    A

-x + 5y+ 12z = 73     B

x + 3y −2z = 1   C

Adding B and C:

8y + 10z = 74 E

Multiply equation B by -3:

-3x - 9y + 6z = -3

Add this equation to A:

-11y + 10z = 17

Subtract this equation fro E:

19y = 57

y = 3.

Substitute y = 3 in equation E:

8*3 + 10z = 74

10z = 50

z = 5.

Finally substitute  y = 3 and z = 5 into equation C:

x + 3(3) - 2(5) = 1

x + 9 - 10 = 1

x = 1 + 1

x = 2.

B) x = 2, y = 3, z = 5

Step-by-step explanation:

3x −2y + 4z = 20

3(2) - 2(3) + 4(5) = 20

20 = 20

−x + 5y +12z = 73

-2 + 5(3) + 12(5) = 73

73 = 73

x + 3y −2z = 1

2 + 3(3) - 2(5) = 1

1 = 1

a) y = -3x +2

b) y = 1/2x -6

these 2 can be combined into one equation.

-3x +2 = .5x -6

8 = 3.5x

x = 8 / 3.5 = 2.2857142857

y = -3 * (8 / 3.5) +2

y = (-24 / 3.5) + 2

y = -4.8571428571

step-by-step explanation: