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Artemon [7]
3 years ago
15

Answer this question: 9x-21=90

Mathematics
2 answers:
maxonik [38]3 years ago
8 0

\text {Hello! Let's Solve this Equation!}

\text {The First Step is to Add 21:}

\text {9x-21+21=90+21}\\\text {9x=111}

\text {The Final Step is to Divide 9:}

\text {9x/9=111/9}

\text {Your Answer would be:}

\fbox {x=37/3}

\text {Best of Luck!}

cestrela7 [59]3 years ago
7 0

Answer:

9x=90+21

9×=111

9×/9 = 111/9

× = 12.33

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Solve for x in the equation x²-12x+59=0
lyudmila [28]

{x}^{2}  - 12x + 59 = 0 \\  {x}^{2}  - 12x + 36 + 23 = 0 \\  {x}^{2}  - 12x + 36 =  - 23 \\  {(x - 6)}^{2}  =  - 23 \\ x - 6 =  +  -  \sqrt{ - 23}  =  +  - i \sqrt{23}  \\ x = 6 +  - i \sqrt{23}

mean

x = 6 + i \sqrt{23}

or

x = 6 - i \sqrt{23}

7 0
3 years ago
Read 2 more answers
With a height of 68 ​in, Nelson was the shortest president of a particular club in the past century. The club presidents of the
Ivahew [28]

Answer:

a. The positive difference between Nelson's height and the population mean is: \\ \lvert 68-70.7 \rvert = \lvert 70.7-68 \rvert\;in = 2.7\;in.

b. The difference found in part (a) is 1.174 standard deviations from the mean (without taking into account if the height is above or below the mean).

c. Nelson's z-score: \\ z = -1.1739 \approx -1.174 (Nelson's height is <em>below</em> the population's mean 1.174 standard deviations units).

d. Nelson's height is <em>usual</em> since \\ -2 < -1.174 < 2.

Step-by-step explanation:

The key concept to answer this question is the z-score. A <em>z-score</em> "tells us" the distance from the population's mean of a raw score in <em>standard deviation</em> units. A <em>positive value</em> for a z-score indicates that the raw score is <em>above</em> the population mean, whereas a <em>negative value</em> tells us that the raw score is <em>below</em> the population mean. The formula to obtain this <em>z-score</em> is as follows:

\\ z = \frac{x - \mu}{\sigma} [1]

Where

\\ z is the <em>z-score</em>.

\\ \mu is the <em>population mean</em>.

\\ \sigma is the <em>population standard deviation</em>.

From the question, we have that:

  • Nelson's height is 68 in. In this case, the raw score is 68 in \\ x = 68 in.
  • \\ \mu = 70.7in.
  • \\ \sigma = 2.3in.

With all this information, we are ready to answer the next questions:

a. What is the positive difference between Nelson​'s height and the​ mean?

The positive difference between Nelson's height and the population mean is (taking the absolute value for this difference):

\\ \lvert 68-70.7 \rvert = \lvert 70.7-68 \rvert\;in = 2.7\;in.

That is, <em>the positive difference is 2.7 in</em>.

b. How many standard deviations is that​ [the difference found in part​ (a)]?

To find how many <em>standard deviations</em> is that, we need to divide that difference by the <em>population standard deviation</em>. That is:

\\ \frac{2.7\;in}{2.3\;in} \approx 1.1739 \approx 1.174

In words, the difference found in part (a) is 1.174 <em>standard deviations</em> from the mean. Notice that we are not taking into account here if the raw score, <em>x,</em> is <em>below</em> or <em>above</em> the mean.

c. Convert Nelson​'s height to a z score.

Using formula [1], we have

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

\\ z = \frac{68\;in - 70.7\;in}{2.3\;in}

\\ z = \frac{-2.7\;in}{2.3\;in}

\\ z = -1.1739 \approx -1.174

This z-score "tells us" that Nelson's height is <em>1.174 standard deviations</em> <em>below</em> the population mean (notice the negative symbol in the above result), i.e., Nelson's height is <em>below</em> the mean for heights in the club presidents of the past century 1.174 standard deviations units.

d. If we consider​ "usual" heights to be those that convert to z scores between minus2 and​ 2, is Nelson​'s height usual or​ unusual?

Carefully looking at Nelson's height, we notice that it is between those z-scores, because:

\\ -2 < z_{Nelson} < 2

\\ -2 < -1.174 < 2

Then, Nelson's height is <em>usual</em> according to that statement.  

7 0
3 years ago
Please help me with this problem. How do I find x?
inysia [295]
Assuming that is 2 right triangles sharing a side
height^2 = 20^2 -7^2
height^2 = 400 - 49
height^2 = 351
height = <span> <span> <span> 18.7349939952 </span> </span> </span>
x^2 = 24^2 - <span>18.7349939952^2
x^2 = 576 -351
x^2 = 225
x = 15

</span>
7 0
2 years ago
What is 9/8 x 1/9 equals what fraction?
Alborosie
\frac{9}{8} * \frac{1}{9}
On multiplying;
\frac{9}{72}
4 0
3 years ago
If sin(A+B)=1/2 &amp; sin(A-B)=1/3 find sin(2A)
timofeeve [1]

Answer:

sin(2A) = (2√2 + √3) / 6

Step-by-step explanation:

2A = (A+B) + (A−B)

sin(2A) = sin((A+B) + (A−B))

Angle sum formula:

sin(2A) = sin(A+B) cos(A−B) + sin(A−B) cos(A+B)

sin(2A) = 1/2 cos(A−B) + 1/3 cos(A+B)

Pythagorean identity:

sin(2A) = 1/2 √[1 − sin²(A−B)] + 1/3 √[1 − sin²(A+B)]

sin(2A) = 1/2 √(1 − 1/9) + 1/3 √(1 − 1/4)

sin(2A) = 1/2 √(8/9) + 1/3 √(3/4)

sin(2A) = 1/3 √2 + 1/6 √3

sin(2A) = (2√2 + √3) / 6

6 0
3 years ago
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