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3 years ago

I need help with all of them and if you can't help with all of them just answer one of them please. Look at the picture

Mathematics

1 answer:

likoan [24]3 years ago

5 0

All you have to do is substitute the y value from the 1st equation into the second equation and solve...

a) y= 2-x
5x + 4y = 5

Substitute (2-x) into the second equation anywhere there is a y...

5x + 4y = 5
5x + 4(2-x) = 5

Now solve

5x + 8 - 4x = 5
5x - 4x + 8 = 5
x + 8 = 5
x = -3

Now that you have a solution for x, substitute -3 into either of the original equations anywhere there is an x then solve for y...

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

You solved for x and got -3 and solved for y and got 5, so your solution set is
(-3, 5).

Now check it by substituting both numbers into one of the original equations and you should have a true statement if it is correct...

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

True statement... it checks!

note* during the check, if the equation would have worked out to something like 2 = 5, then that is a false statement therefore the solution set would be wrong and you'd have to go back and find the mistake.

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PLEASE HELP!<br> Question in picture below!

qaws [65]

Answer:

x = 13/8

Step-by-step explanation:

sqrt(8x-4) +8 = 11

Subtract 8 from each side

sqrt(8x-4) +8-8 = 11-8

sqrt(8x-4) =3

Square each side

(sqrt(8x-4))^2 =3^2

8x-4 = 9

Add 4 to each side

8x-4+4 = 9+4

8x = 13

Divide by 8

8x/8 = 13/8

x = 13/8

6 0

3 years ago

Help:

dalvyx [7]

Answer:

Step-by-step explanation:

a. (11x) + (22x)= 33x

b. (-6x) - (-6x) = 0

c. (-13) + (14x) - (+13t) = -13t + 14x - 13

d. (-4t) + (+4t) - (-6t) = 6t

4 0

3 years ago

Read 2 more answers

When the sum of an unknown number and twenty two is divided by the unknown number, the quotient is 12. What is the unknown numbe

Gnom [1K]

You would basically work backwards and do inverse operations

12
24*
__
288

288/24= 12

8 0

3 years ago

Your state is considering raising the legal age for consumption of alcoholic beverages to 21 years old. How large a sample size

julsineya [31]

Answer:

$n=\frac{0.5(1-0.5)}{(\frac{0.01}{2.58})^2}=16641$

And rounded up we have that n=16641

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".

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{p(1-p)}{n}})$

Solution to the problem

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 99% of confidence, our significance level would be given by $\alpha=1-0.99=0.01$ and $\alpha/2 =0.005$ . And the critical value would be given by:

$z_{\alpha/2}=-2.58, t_{1-\alpha/2}=2.58$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.01$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

For this case we can use as estimator for the proportion $\hat p =0.5$ , since we don't have any other previous info. And replacing into equation (b) the values from part a we got: