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Eduardwww [97]
3 years ago
14

1) 2x – 3y - z = 7

Mathematics
1 answer:
m_a_m_a [10]3 years ago
5 0

Answer:

x = 3

Step-by-step explanation:

2x - 3y - z = 7 (equation 1)

3x + 5y - 3z = -2 (equation 2)

4x – y + 2z = 17 (equation 3)

(1) * 3 : 6x - 9y - 3z = 21 (1)'

(1)' - (2) :  3x - 14 y = 23 (equation 4)

(1) * 2 : 4x - 6y - 2z = 14 (1)"

(1)" + (3) : 8x - 7y = 31 (equation 5)

(5)*2 : 16x - 14y = 62 (5)'

(5)' - (4) : 13x = 39

              x = 3

So thus, x = 3 in this system of equations, you can plug x back into equation 4 or 5 to find y and then plug x and y back into equations 1, 2, or 3 to find z

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The manager of a grocery store has selected a random sample of 100 customers. The average length of time it took these 100 custo
SSSSS [86.1K]

Answer:

The 95% confidence interval would be given by (2.804;3.196)    

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

\bar X=3.0 represent the sample mean  

\mu population mean (variable of interest)

\sigma=1 represent the population standard deviation

n=100 represent the sample size  

The confidence interval for the mean is given by the following formula:

\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}   (1)

Since the Confidence is 0.95 or 95%, the value of \alpha=0.05 and \alpha/2 =0.025, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.025,0,1)".And we see that z_{\alpha/2}=1.96

Now we have everything in order to replace into formula (1):

3.0-1.96\frac{1}{\sqrt{100}}=2.804    

3.0+1.96\frac{1}{\sqrt{10}}=3.196

So on this case the 95% confidence interval would be given by (2.804;3.196)    

4 0
3 years ago
Find a solution for 5x+4y=-30 and 3x-9y=-18
Dahasolnce [82]

{5x + 4y = -30

{3x - 9y = -18        | : 3

{5x + 4y = -30

{x - 3y = -6          | + 3y

{5x + 4y = -30

{x = 3y - 6

{5(3y - 6) + 4y = -30

{x = 3y - 6

{15y - 30 + 4y = -30         | + 30

{x = 3y - 6

{19y = 0              | : 19

{x = 3y - 6

{y = 0

{x = 3 · 0 - 6

{y = 0

{x = -6

3 0
3 years ago
The distance d of a particle moving in a straight line is given by d(t) = 2t3 + 5t – 2, where t is given in seconds and d is mea
Sergeeva-Olga [200]

Answer:

(C)6t^2+5

Step-by-step explanation:

Given the distance, d(t) of a particle moving in a straight line at any time t is:

d(t) = 2t^3 + 5t - 2, $ where t is given in seconds and d is measured in meters.

To find an expression for the instantaneous velocity v(t) of the particle at any given point in time, we take the derivative of d(t).

v(t)=\dfrac{d}{dt}\\\\v(t) =\dfrac{d}{dt}(2t^3 + 5t - 2) =3(2)t^{3-1}+5t^{1-1}\\\\v(t)=6t^2+5

The correct option is C.

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3 years ago
Simplify 150 -(0.4 x 150)+15
Rufina [12.5K]
150-(0.4 x 150)+15= 105
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