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3 years ago

Solve the system by substitution 5x+y=-14 5x- 3y=2

Mathematics

1 answer:

dlinn [17]3 years ago

8 0

Answer:

x = -2, y = -4, or (-2, -4).

Step-by-step explanation:

5x + y = -14

5x - 3y = 2

If we look at the first equation, we can see that y can be easily isolated.

5x + y = -14

Subtract 5x from both sides.

y = -5x - 14

Now we have a variable that we can plug into the second equation.

5x - 3y = 2

5x - 3(-5x - 14) = 2

Distribute the -3 across each term in the parentheses.

5x + 15x + 42 = 2

Combine like terms.

20x + 42 = 2

Subtract 42 from both sides.

20x = -40

Divide both sides by 20 to isolate x.

x = -2

Plug in x = -2 back into one of the equations to find y.

y = -5x - 14

y = -5(-2) - 14

Multiply.

y = 10 - 14

Subtract.

y = -4

Our solution is x = -2, y = -4, or (-2, -4).

Check your answer by plugging both values into one of the equations.

5x - 3y = 2

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

-10 + 12 = 2

2 = 2

Your answer is correct.

Hope this helps!

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The proportion of the population that have a protein requirement less than 0.60 g P • kg-1 • d-1 is 0.239, that is, 239 persons for every 1000, or simply 23.9% of them.

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Step-by-step explanation:

From the question, we have the following information:

The distribution for protein requirement is normally distributed.
The population mean for protein requirement for adults is $\\ \mu= 0.65 gP*kg^{-1}*d^{-1}$
The population standard deviation is $\\ \sigma =0.07 gP*kg^{-1}*d^{-1}$

We have here that protein requirements in adults is normally distributed with defined parameters. The question is about the proportion of the population that has a requirement less than $\\ x = 0.60 gP*kg^{-1}*d^{-1}$ .

For answering this, we need to calculate a z-score to obtain the probability of the value x in this distribution using a standard normal table available on the Internet or on any statistics book.

<h3>z-score</h3>

A z-score is expressed as

$\\ z = \frac{x - \mu}{\sigma}$

For the given parameters, we have:

$\\ z = \frac{0.60 - 0.65}{0.07}$

$\\ z = -0.7142857$

<h3>Determining the probability</h3>

With this value for z at hand, we need to consult a standard normal table to determine what the probability of this value is.

The value for z = -0.7142857 is telling us that the requirement for protein is below the population mean (negative sign indicates this). However, most standard normal tables give a probability that a statistic is less than z and for values greater than the mean (in other words, positive values). To overcome this, we need to take the complement of the probability given for z-score z = 0.7142857, that is, subtract from 1 this probability, which is possible because the normal distribution is symmetrical.

Tables have values for z with two decimal places, then, for z = 0.7142857, we need to rewrite it as z = 0.71. For this value, the standard normal table gives a value of P(z<0.71) = 0.76115.

Therefore, the cumulative probability for values less than x = 0.60 which corresponds to a z-score = -0.7142857 is approximately:

$\\ P(x$