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3 years ago

Evaluate the following expression when x=3. 2x+7

Mathematics

1 answer:

xxMikexx [17]3 years ago

6 0

Answer:13

Step-by-step explanation:

2 times 3 is 6 so then we add 7 to get 13

You might be interested in

A number is squared. The result is squared, then that result is squared. The final number is 6561. What was the original number?

MissTica

The original number is 3.

I actually began with the guess-and-check method, but seeing as that won't always work, let's go over the formal way. To get the original number, you first need to determine how many times the number was squared.

To make it simple, let's use x to focus on the exponents. The number was squared 3 times, so x^2, x^2, x^2. Basically, you need to multiply. 2 * 2 * 2 = 8. So, now find the 8th root of 6561 (depending on the calculator, you can just input it). You should come up with 3. Let me know if this part confuses you.

To find the next 2 numbers, you just need to continue the pattern.

6561^2 = 43,046,721

43,046,721^2 = 1,853,020,188,851,841

To my knowledge, which means this could be wrong, they're both perfect squares. Since the number to get them both were whole numbers, they should both have a square root that equals a whole number.

3 0

3 years ago

A teacher was interested in knowing the amount of physical activity that his students were engaged in daily. He randomly sampled

klasskru [66]

Answer:

The standard error of the mean is 4.5.

Step-by-step explanation:

As we don't know the standard deviation of the population, we can estimate the standard error of the mean from the standard deviation of the sample as:

$\sigma_{\bar{x}}\approx\frac{s}{\sqrt{n}}$

The sample is [30mins, 40 mins, 60 mins, 80 mins, 20 mins, 85 mins]. The size of the sample is n=6.

The mean of the sample is:

$\bar{x}=\frac{1}n} \sum x_i =\frac{30+40+60+80+20+85}{6}=52.5$

The standard deviation of the sample is calculated as:

$s=\sqrt{\frac{1}{n-1}\sum (x_i-\bar x)^2} \\\\ s=\sqrt{\frac{1}{5}\cdot ((30-52.5)^2+(40-52.5)^2+(60-52.5)^2+(80-52.5)^2+(20-52.5)^2+(85-52.5)^2}\\\\s=\sqrt{\frac{1}{5} *3587.5}=\sqrt{717.5}=26.8$

Then, we can calculate the standard error of the mean as:

$\sigma_{\bar{x}}\approx\frac{s}{\sqrt{n}}=\frac{26.8}{6}= 4.5$

6 0

3 years ago

You are debating about whether to buy a new computer for $800.00 or a refurbished computer with the same equipment for $640.00.

Xelga [282]

The difference
800−640
=160

160×(1+0.045)
=167.2

3 0

3 years ago

Read 2 more answers

Malik, who is 5 feet tall, stands 15 feet from a mirror. In the mirror, he can see the reflection of the top of a tree, which he

Goryan [66]

Answer:

I don't get the question?? What is the question??

Step-by-step explanation:

4 0

2 years ago

A bus covers a distance of 90km at a uniform speed. Had the speed been 15km/hour it would have taken 30 minutes less for the jou

Brrunno [24]

Answer:

Step-by-step explanation

Let's say d = distance, r = speed and t = time

We know the distance formula is :

distance = speed x time

d = r multiplied by t

d = rt

If the speed is 15km/hr, the time would be 30 minutes shorter.

Since d = rt,

90 = 15t

t = 6,

This means the time taken for the bus to complete the journey at 15km/hr would be 6hrs.

Originally though, the journey takes 30 minutes longer.

So we can say t = 6.5 hrs , and we know d = 90

Now we use the distance formula:

d = rt, since we want to find the original speed, we want to find r.

Speed = distance/time

r = d/t

r = 90/6.5

r = 180/13

Therefore the original speed is 180/13 km/hr

4 0

3 years ago