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hammer [34]
3 years ago
10

Solve for x, y, and z. y=1/2z x+2y+5z=2 3x+6y-3z=9

Mathematics
1 answer:
Contact [7]3 years ago
7 0
Rearrange the equation,

0x + y - ½z = 0 ==> Equation 1
x + 2y + 5z = 2 ==> Equation 2
3x + 6y - 3z = 9 ==> Equation 3

Put the 3 equation in matrix form,

0\ \ \ \ \ 1\ \ -{\frac{1}{2} }\ \ \ \ \ \ \ \ 0 \\ 1\ \ \ \ \ 2\ \ \ \ \ \ \ 5\ \ =\ 2 \\ 3\ \ \ \ \ 6\ \ -3\ \ \ \ \ \ \ \ \ 9

Find the determinant, D, of the matrix,

0\ \ \ \ \ 1\ \ -{\frac{1}{2} } \\ 1\ \ \ \ \ 2\ \ \ \ \ \ \ 5\ = \ D \\ 3\ \ \ \ \ 6\ \ -3

By Sarrus' rule,
D = [(0 × 2 × -3) + (1 × 5 × 3) + (-½ × 1 × 6)] - [(-½ × 2 × 3) + (5 × 6 × 0) + (-3 × 1 × 1)]
D = [0 + 15 + (-3)] - [(-3) + 0 + (-3)]
D = 12 + 6
D = 18

By cramer's rule,

x = Determinant of x ÷ D
Let determinant of x = Dx,

0\ \ \ \ \ 1\ \ -{\frac{1}{2} } \\ 2\ \ \ \ \ 2\ \ \ \ \ \ \ 5\ = \ Dx \\ 9\ \ \ \ \ 6\ \ -3
To get this determinant, substitude 0, 2 and 9 with the unknown you're finding, in this case, x.

By Sarrus' rule,
Dx = [(0 × 2 × -3) + (1 × 5 × 9) + (-½ × 2 × 6)] - [(-½ × 2 × 9) + (0 × 5 × 6) + (-3 × 1 × 2)]
Dx = [0 + 45 + (-6)] - [-9 + 0 + (-6)]
Dx = 39 + 15
Dx = 54

x = Dx ÷ D
x = 54 ÷ 18
x = 3

By cramer's rule,

y = Determinant of y ÷ D
Let determinant of y = Dy

0\ \ \ \ \ 0\ \ -{\frac{1}{2} } \\ 1\ \ \ \ \ 2\ \ \ \ \ \ \ 5\ = \ Dy \\ 3\ \ \ \ \ 9\ \ -3

By Sarrus' rule,
Dy = [(0 × 2 × -3) + (0 × 5 × 3) + (-½ × 1 × 9)] - [(-½ × 2 × 3) + (5 × 9 × 0) + (-3 × 0 × 1)
Dy = [0 + 0 - 4½] - [-3 + 0 + 0]
Dy = -4½ + 3
Dy = -1½

y = Dy ÷ D
y = -1½ ÷ 18
y ≈ 0.0833 (3 significant figure)

Solving z using equation rule,
y = ½z
0.0833 = ½z
z = 0.0833 ÷ ½
z ≈ 0.167 (3 significant figure)

∴ x = 3, y = 0.0833 and z = 0.167.
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Compare the graph of f (x) with the graph of k (x) = 2 (x-8)2
Bingel [31]

Answer:

one is not linear

Step-by-step explanation:

7 0
3 years ago
To complete a task in 15 days, a company has 4 people each working 8 hours a day. The company
Klio2033 [76]

Answer:

Let's suppose that each person works at an hourly rate R.

Then if 4 people working 8 hours per day, a total of 15 days to complete the task, we can write this as:

4*R*(15*8 hours) = 1 task.

Whit this we can find the value of R.

R = 1 task/(4*15*8 h) = (1/480) task/hour.

a) Now suppose that we have 5 workers, and each one of them works 6 hours per day for a total of D days to complete the task, then we have the equation:

5*( (1/480) task/hour)*(D*6 hours) = 1 task.

We only need to isolate D, that is the number of days that will take the 5 workers to complete the task:

D = (1 task)/(5*6h*1/480 task/hour) = (1 task)/(30/480 taks) = 480/30 = 16

D = 16

Then the 5 workers working 6 hours per day, need 16 days to complete the job.

b) The assumption is that all workers work at the same rate R. If this was not the case (and each one worked at a different rate) we couldn't find the rate at which each worker completes the task (because we had not enough information), and then we would be incapable of completing the question.

4 0
3 years ago
Rita makes and sells necklaces. The materials to make each necklace cost $2.75. Last week she made 8 necklaces and wants to make
Tresset [83]

Answer:

The error she made was that she was adding x and 2.75. She should subtract 2.75 from x.

Another mistake that she made was that she sold each for $7 assuming that she would make a profit of 78, but she should see each necklace for $12.5 so that she could make a profit of $78.

Step-by-step explanation:

The error she made was that she was adding x and 2.75.

She should write the equation as 8 (x - 2.75) = 78; as she spends $2.75 to make a necklace.

By using the correct equation: 8 (x - 2.75) = 78

=> 8x - 22 = 78

=> 8x = 78 + 22

=> 8x = 100

=> x = 100/8

=> x = 12.5

Another mistake that she made was that she sold each for $7 assuming that she would make a profit of 78, but she should see each necklace for $12.5 so that she could make a profit of $78.

Hope this helps you.

3 0
2 years ago
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