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Morgarella [4.7K]
3 years ago
6

Abby surveys every 25th sutend from an alphabetized list of students.l in the school. is this a representative sapmle at Abby's

school? Explain.
Mathematics
1 answer:
Roman55 [17]3 years ago
4 0
Yes, because the sample is random. If she had chosen the participants in any way other than randomly, it would not be representative of her entire school.
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Solve the system of linear equations using the Gauss-Jordan elimination method. 2x + 3y 6212 3x + (x, y. z)
Gekata [30.6K]

Answer:

The solution of the system of linear equations is x=3, y=4, z=1

Step-by-step explanation:

We have the system of linear equations:

2x+3y-6z=12\\x-2y+3z=-2\\3x+y=13

Gauss-Jordan elimination method is the process of performing row operations to transform any matrix into reduced row-echelon form.

The first step is to transform the system of linear equations into the matrix form. A system of linear equations can be represented in matrix form (Ax=b) using a coefficient matrix (A), a variable matrix (x), and a constant matrix(b).

From the system of linear equations that we have, the coefficient matrix is

\left[\begin{array}{ccc}2&3&-6\\1&-2&3\\3&1&0\end{array}\right]

the variable matrix is

\left[\begin{array}{c}x&y&z\end{array}\right]

and the constant matrix is

\left[\begin{array}{c}12&-2&13\end{array}\right]

We also need the augmented matrix, this matrix is the result of joining the columns of the coefficient matrix and the constant matrix divided by a vertical bar, so

\left[\begin{array}{ccc|c}2&3&-6&12\\1&-2&3&-2\\3&1&0&13\end{array}\right]

To transform the augmented matrix to reduced row-echelon form we need to follow these row operations:

  • multiply the 1st row by 1/2

\left[\begin{array}{ccc|c}1&3/2&-3&6\\1&-2&3&-2\\3&1&0&13\end{array}\right]

  • add -1 times the 1st row to the 2nd row

\left[\begin{array}{ccc|c}1&3/2&-3&6\\0&-7/2&6&-8\\3&1&0&13\end{array}\right]

  • add -3 times the 1st row to the 3rd row

\left[\begin{array}{ccc|c}1&3/2&-3&6\\0&-7/2&6&-8\\0&-7/2&9&-5\end{array}\right]

  • multiply the 2nd row by -2/7

\left[\begin{array}{ccc|c}1&3/2&-3&6\\0&1&-12/7&16/7\\0&-7/2&9&-5\end{array}\right]

  • add 7/2 times the 2nd row to the 3rd row

\left[\begin{array}{ccc|c}1&3/2&-3&6\\0&1&-12/7&16/7\\0&0&3&3\end{array}\right]

  • multiply the 3rd row by 1/3

\left[\begin{array}{ccc|c}1&3/2&-3&6\\0&1&-12/7&16/7\\0&0&1&1\end{array}\right]

  • add 12/7 times the 3rd row to the 2nd row

\left[\begin{array}{ccc|c}1&3/2&-3&6\\0&1&0&4\\0&0&1&1\end{array}\right]

  • add 3 times the 3rd row to the 1st row

\left[\begin{array}{ccc|c}1&3/2&0&9\\0&1&0&4\\0&0&1&1\end{array}\right]

  • add -3/2 times the 2nd row to the 1st row

\left[\begin{array}{ccc|c}1&0&0&3\\0&1&0&4\\0&0&1&1\end{array}\right]

From the reduced row echelon form we have that

x=3\\y=4\\z=1

Since every column in the coefficient part of the matrix has a leading entry that means our system has a unique solution.

7 0
3 years ago
Which figure does NOT appear to be a parallelogram ?
cupoosta [38]

Answer:

B) Figure 2

Explanation:

In all parallelograms, both pairs of opposite sides are parallel to each other. Thus the name parallelogram. Figure 1, figure 2 , and figure 4 all share that property. Figure 2 does not, as it only has one pair of opposite sides parallel to each other. It is a trapezoid.

3 0
3 years ago
Tue 2 NOV moe.alefed.com 71. Check My Understanding 2 Khadija and Muneera are sisters. Together they have 15 dolls. Muneera has
tigry1 [53]

Answer:

hhsnghh sihdg hhurihhspig

Step-by-step explanation:

shhgnshhistdh shdj

5 0
2 years ago
I need help on algebra
boyakko [2]
Just remember the syllables PEMDAS which stand for Parentheses, Exponents, Multiplication, Division, Addition and Subtraction. If you can’t remember it, just write it on the side of your paper. But make sure to use it in that order.
5 0
3 years ago
Read 2 more answers
When the volume of a gas is
Fudgin [204]

Answer: The initial volume is 593.76mL

Step-by-step explanation:

As you do not say anithing about the pressure, i guess that the pressure remains constant.

If the gas is an ideal gas, we have:

P*V = n*R*T

where P is pressure, n is number of moles and R is a constant.

Now, initially we have:

P*Vi = n*R*315°C

finally we have:

P*825mL = n*R*452°C

Now we can take the quiotient of those two equations and get:

(P*Vi)/(P*852mL) = (n*R*315°C)/( n*R*452°C)

Now we have:

Vi/852mL = 315/452

Vi =  (315/452)*852mL = 593.76mL

So when we expand the gas at constant pressure, we increase the temperature.  

3 0
3 years ago
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