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1 year ago

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The graph of f(x) = 4x3 – 13x2 + 9x + 2 is shown below. On a coordinate plane, a function is shown. The function starts from the

bottom of quadrant 3 and goes up through the x-axis at (0, negative 0.25) and then through the y-axis at (0, 2). It then starts to curve down at (0.5, 4) until it reaches (1.75, negative 0.5). It then curves up and crosses the x-axis at (2, 0) and goes up approaching x = 3. How many roots of f(x) are rational numbers? 0 1 2 3

1 answer:

iris [78.8K]1 year ago

6 0

Answer:

3

Step-by-step explanation:

f(x) = 4x^3 – 13x^2 + 9x + 2

This looks complicated but all we need to find are the Roots

We are looking for when y=0

So given each part of the information, we can label how many times it happens

<em>The function starts from the bottom of quadrant 3: </em><u>Starts lower left</u>

<em> and goes up through the x-axis at (0, negative 0.25) </em>: This is ONE ROOT

<em>and then through the y-axis at (0, 2). : It's now on the 2nd quartile</em>

<em>It then starts to curve down at (0.5, 4): It's moving towards y=0</em>

<em>until it reaches (1.75, negative 0.5).: </em>It has now passed y=o and there are TWO ROOTS

<em> It then curves up and crosses the x-axis at (2, 0) and goes up approaching x = 3: </em>It has passed y=0 again, so there are THREE ROOTS

This polynomial function has 3 ROOTS

<em />

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$1.667-2.31\frac{1.803}{\sqrt{9}}=0.2789$

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The 95% confidence interval to judge whether the two indeners result in different measurements is?

Yes the confidence interval not contains the value 0 so we can conclude that the values for Diamond are significantly higher than the values for Steel Ball at 5% of significance.

Step-by-step explanation:

We have the following dataset:

specimen 1 2 3 4 5 6 7 8 9

Steel Ball 51 57 61 70 68 54 65 51 53

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If we calculate the differences diamond-steel ball we have this datase:

d: 2, -2, 2, 4, 1, 2, 3, 0, 3

The second step is calculate the mean difference

$\bar d= \frac{\sum_{i=1}^n d_i}{n}=1.667$

The third step would be calculate the standard deviation for the differences, and we got:

$s_d =\frac{\sum_{i=1}^n (d_i -\bar d)^2}{n-1} =1.803$

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".

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In order to calculate the critical value $t_{\alpha/2}$ we need to find first the degrees of freedom, given by:

$df=n-1=9-1=8$

Since the confidence is 0.95 or 95%, the value of $\alpha=0.05$ and $\alpha/2 =0.025$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,9)".And we see that $t_{\alpha/2}=2.31$ .

Now we have everything in order to replace into formula (1):

$1.667-2.31\frac{1.803}{\sqrt{9}}=0.2789$

$1.667+2.31\frac{1.803}{\sqrt{9}}=3.055$

So on this case the 95% confidence interval would be given by (0.2789;3.055)

The 95% confidence interval to judge whether the two indeners result in different measurements is?

Yes the confidence interval not contains the value 0 so we can conclude that the values for Diamond are significantly higher than the values for Steel Ball at 5% of significance.

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