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ioda
3 years ago
5

Find the product of all real values of r for which 1/2x=r-x/7

Mathematics
1 answer:
Dahasolnce [82]3 years ago
8 0

Answer:

r = \±\sqrt{14

Product = -14

Step-by-step explanation:

Given

\frac{1}{2x} = \frac{r - x}{7}

Required

Find all product of real values that satisfy the equation

\frac{1}{2x} = \frac{r - x}{7}

Cross multiply:

2x(r - x) = 7 * 1

2xr - 2x^2 = 7

Subtract 7 from both sides

2xr - 2x^2 -7= 7 -7

2xr - 2x^2 -7= 0

Reorder

- 2x^2+ 2xr  -7= 0

Multiply through by -1

2x^2 - 2xr +7= 0

The above represents a quadratic equation and as such could take either of the following conditions.

(1) No real roots:

This possibility does not apply in this case as such, would not be considered.

(2) One real root

This is true if

b^2 - 4ac = 0

For a quadratic equation

ax^2 + bx + c = 0

By comparison with 2x^2 - 2xr +7= 0

a = 2

b = -2r

c =7

Substitute these values in b^2 - 4ac = 0

(-2r)^2 - 4 * 2 * 7 = 0

4r^2 - 56 = 0

Add 56 to both sides

4r^2 - 56 + 56= 0 + 56

4r^2 = 56

Divide through by 4

r^2 = 14

Take square roots

\sqrt{r^2} = \±\sqrt{14

r = \±\sqrt{14

Hence, the possible values of r are:

\sqrt{14 or -\sqrt{14

and the product is:

Product = \sqrt{14} * -\sqrt{14}

Product = -14

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I'd go with answer C!
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3 years ago
Solve equation x-9= -12
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Step-by-step explanation:

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3 0
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UkoKoshka [18]

Answer:

C. 5.2 cm

Step-by-step explanation:

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s = \dfrac{n}{360^\circ} 2 \pi r

where s = arc length

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diamter = d = 10 cm

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s = \dfrac{n}{360^\circ} 2 \pi r

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Answer:

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In order to satisfy this distribution we need that each observation on this case comes from a normal distribution, because since the sample size is not large enough we can't apply the central limit theorem.

Step-by-step explanation:

For this case we have that the sample size is n =6

The sample man is defined as :

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So for this case we need to satisfy the following condition:

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Because if we find the parameters we got:

E(\bar X) =\frac{1}{n} \sum_{i=1}^n E(X_i) = \frac{n\mu}{n}=\mu

Var(\bar X)= \frac{1}{n^2} \sum_{i=1}^n Var(X_i) = \frac{n\sigma^2}{n^2}= \frac{\sigma^2}{n}

And the deviation would be:

Sd (\bar X) = \frac{\sigma}{\sqrt{n}}

And we satisfy the condition:

\bar X \sim N(\mu , \frac{\sigma}{\sqrt{n}})

3 0
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