All categories

3 years ago

3x - y = 7 y = 2x - 2

Mathematics

1 answer:

____ [38]3 years ago

5 0

Answer:

x = 9

Step-by-step explanation:

1) Subsitute! You have to replace y with 2x - 2 in 3x -y = 7, b/c they already gave you the equation for y (in the second part: y = 2x - 2)

So, your equation would look like this : 3x - (2x - 2) = 7

3) Solve suing PEMDAS!

There's a negative outside the parenthesis of 2x -2 -> - (2x-2). Multiply the negative individually inside the parenthesis so you will get (-2x + 2)

3x - 2x - 2 = 7 subtract the same variable; x

1x - 2 = 7 you don't need to put 1 to x, only if you want!

+ 2 + 2 add 2 on both sides

x = 9

You might be interested in

How do u order decimals ??

Furkat [3]

Answer:

To order decimals, you first need a range of values.

Step-by-step explanation:

For example, if there are 5 values: 0.25, 0.87,0.19,0.89 and 0.98

First, look at the first digit after the decimal. The smallest digit is the smallest so far. In this case, it is 0.19 as '1' was the smallest digit. Second would be 0.25 because 2 is the second smallest digit here.

Now, we have 3 remaining numbers: 0.87, 0.89 and 0.98

You can notice that both 0.87 and 0.89 have the same first digit after the decimal.

Do fix this problem, look at the second digit and decide the smallest one. In this case, it is 0.87.

This means the order will go like this if it is smallest to largest: 0.19, 0.25, 0.87, 0.89, 0.98.

If it is largest to smallest, do it the other way around.

Hope this helped!

4 0

2 years ago

An appliance manufacturer claims to have developed a compact microwave oven that consumes a mean of no more than 250 W. From pre

melamori03 [73]

Answer:

We conclude that a compact microwave oven consumes a mean of more than 250 W.

Step-by-step explanation:

We are given that an appliance manufacturer claims to have developed a compact microwave oven that consumes a mean of no more than 250 W with a population standard deviation of 15 W.

They take a sample of 20 microwave ovens and find that they consume a mean of 257.3 W.

Let $\mu$ = mean power consumption for microwave ovens.

So, Null Hypothesis, $H_0$ : $\mu$ $\leq$ 250 W {means that a compact microwave oven consumes a mean of no more than 250 W}

Alternate Hypothesis, $H_A$ : $\mu$ > 250 W {means that a compact microwave oven consumes a mean of more than 250 W}

The test statistics that would be used here One-sample z test statistics as we know about the population standard deviation;

T.S. = $\frac{\bar X-\mu}{\frac{\sigma}{\sqrt{n} } }$ ~ N(0,1)

where, $\bar X$ = sample mean power consumption for ovens = 257.3 W

σ = population standard deviation = 15 W

n = sample of microwave ovens = 20

So, the test statistics = $\frac{257.3-250}{\frac{15}{\sqrt{20} } }$

= 2.176

The value of z test statistics is 2.176.

Now, at 0.05 significance level the z table gives critical value of 1.645 for right-tailed test.

Since our test statistic is more than the critical value of t as 2.176 > 1.645, so we have sufficient evidence to reject our null hypothesis as it will fall in the rejection region due to which we reject our null hypothesis.

Therefore, we conclude that a compact microwave oven consumes a mean of more than 250 W.

7 0

3 years ago

When 4 is subtracted from the square of a number, the result is 3 times the number. Find the positive solution

vitfil [10]

Answer is 4 = x. Write out The equation. Then converted to a polynomial. Then use the formula in the top upper right and then do the simple arithmetic to find a positive solution for X. it also makes logical sense as well, 3×4 is 12. I hope this helps and makes sense my Hand writing is not the Best

8 0

3 years ago

In the rectangle below, AE=2x+8, CE=5x+4, and m

ICE Princess25 [194]

Answer: 2x+8=12, 5x+4=29

Step-by-step explanation:

2x2=4+8=12

5x5=25+4=29

7 0

3 years ago

The weight of an adult swan is normally distributed with a mean of 26 pounds and a standard deviation of 7.2 pounds. A farmer ra

Snezhnost [94]

Let $X$ denote the random variable for the weight of a swan. Then each swan in the sample of 36 selected by the farmer can be assigned a weight denoted by $X_1,\ldots,X_{36}$ , each independently and identically distributed with distribution $X_i\sim\mathcal N(26,7.2)$ .

You want to find

$\mathbb P(X_1+\cdots+X_{36}>1000)=\mathbb P\left(\displaystyle\sum_{i=1}^{36}X_i>1000\right)$

Note that the left side is 36 times the average of the weights of the swans in the sample, i.e. the probability above is equivalent to

$\mathbb P\left(36\displaystyle\sum_{i=1}^{36}\frac{X_i}{36}>1000\right)=\mathbb P\left(\overline X>\dfrac{1000}{36}\right)$

Recall that if $X\sim\mathcal N(\mu,\sigma)$ , then the sampling distribution $\overline X=\displaystyle\sum_{i=1}^n\frac{X_i}n\sim\mathcal N\left(\mu,\dfrac\sigma{\sqrt n}\right)$ with $n$ being the size of the sample.

Transforming to the standard normal distribution, you have

$Z=\dfrac{\overline X-\mu_{\overline X}}{\sigma_{\overline X}}=\sqrt n\dfrac{\overline X-\mu}{\sigma}$

so that in this case,

$Z=6\dfrac{\overline X-26}{7.2}$

and the probability is equivalent to

$\mathbb P\left(\overline X>\dfrac{1000}{36}\right)=\mathbb P\left(6\dfrac{\overline X-26}{7.2}>6\dfrac{\frac{1000}{36}-26}{7.2}\right)$
$=\mathbb P(Z>1.481)\approx0.0693$

5 0

3 years ago