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s344n2d4d5 [400]
2 years ago
15

Solve 9x^2- 17x- 85 = 0 Give your solutions correct to 3 significant figures.​

Mathematics
1 answer:
dybincka [34]2 years ago
4 0

Answer:

x =\frac{17}{18} +\frac{1}{18} \sqrt{3349} OR x =\frac{17}{18} +\frac{-1}{18} \sqrt{3349}

Step-by-step explanation:

9x2−17x−85=0

For this equation: a=9, b=-17, c=-85

9x2+−17x+−85=0

Step 1: Use quadratic formula with a=9, b=-17, c=-85.

x =\frac{-b + \sqrt{b^{2}-4ac } }{2a}

x  =\frac{-(-17)+\sqrt{(-17)^{2} -4(9)(-85)} }{2(9)}

x =\frac{17}{18} +\frac{-1}{18} \sqrt{3349}

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Can I please get help? Find M1 and M2
marishachu [46]

Answer:

m∠1 = 110° and m∠2 = 70°

Step-by-step explanation:

m∠1 = 110° since vertical angles

To find m∠2, m∠1 and m∠2 must add to 180°

m∠1 + m∠2 = 180°

110° + m∠2 = 180°

m∠2 = 70°

8 0
2 years ago
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
What was Zane's unit rate, in words per minute, on each test?
AfilCa [17]

Answer:

Test A: 40 words per minute

Test B: 54 words per minute

Test C: 44 words per minute

<em><u>Test B has the highest unit rate</u></em>

Step-by-step explanation:

Test A divide 30 by \frac{3}{4} (30/0.75=40)

Test B divide 78 by 1\frac{1}{2} (78/1.5=52)

Test C divide 99 by 2\frac{1}{4} (99/2.25=44)

<u>Hope this helps :-)</u>

<u />-noorati<u />

4 0
2 years ago
Find the logarithmic function y = logbx that passes through the points
katovenus [111]

b\in(0,\ 1)\ \cup\ (1,\ \infty)\\x > 0\\y\in\mathbb{R}\\--------------------------\\\\y=\log_bx\\\\For\ (1,\ 0)\to x=1,\ y=0.\ Substitute:\\\\\log_b1=0\to b^0=1\to b\in(0,\ 1)\ \cup\ (1,\ \infty)\\\\For\ (116,\ 2)\to x=116,\ y=2.\ Substitute:\\\\\log_b116=2\to b^2=116\to b=\sqrt{116}\\\to b=\sqrt{4\cdot29}\to b=\sqrt4\cdot\sqrt{29}\to b=2\sqrt{29}\\\\For\ (4,\ -1)\to x=4,\ y=-1.\ Substitute:\\\\\log_b4=-1\to b^{-1}=4\to b=\dfrac{1}{4}

Different values of b.

<h3>Answer: There is no logarithmic function whose graph goes through given points.</h3><h3 />

Maybe the second point is \left(\dfrac{1}{16},\ 2\right)

Substitute:

\log_b\dfrac{1}{16}=2\to b^2=\dfrac{1}{16}\to b=\sqrt{\dfrac{1}{16}}\to b=\dfrac{1}{4}

<h3>Then we have the answer:</h3>

\boxed{y=\log_{\frac{1}{4}}x}

6 0
3 years ago
7/9 ÷ 3/9 = ????????
Gennadij [26K]

7/9 ÷ 3/9 =

= (7•9)/( 3•9)

= 63/27 = 7/3

Answer is 7/3

6 0
1 year ago
Read 2 more answers
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