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3 years ago

Solve x^2-8x-9=0 using completing the square (show the work)

Mathematics

1 answer:

Elden [556K]3 years ago

3 0

Answer: x=9,-1

Step-by-step explanation:

First, we are gonna start out with finding two numbers that multiply to equal -9 and add up to equal -8

Those numbers would be -9 & 1

-9+1=-8

-9x1=-9

Now we have

(x-9)(x+1)

x-9=0 x+1=0

+9 +9 -1 -1

x=9 x=-1

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Suppose we are testing the null hypothesis H 0 mu=20 and the alternative H iu =20 , normal population with sigma=6 A random samp

cupoosta [38]

Answer:

The value of the test statistic is $z = -1.5$

Step-by-step explanation:

The formula for the test statistic is:

$z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}$

In which X is the statistic, $\mu$ is the mean, $\sigma$ is the standard deviation and n is the number of observations.

In this problem, we have that:

$\mu = 20, X = 17, \sigma = 6, n = 9$

$z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}$

$z = \frac{17 - 20}{\frac{6}{\sqrt{3}}}$

$z = -1.5$

The value of the test statistic is $z = -1.5$

8 0

3 years ago

a. Fill in the midpoint of each class in the column provided. b. Enter the midpoints in L1 and the frequencies in L2, and use 1-

Tresset [83]

Answer:

$\begin{array}{ccc}{Midpoint} & {Class} & {Frequency} & {64} & {63-65} & {1} & {67} & {66-68} & {11} & {70} & {69-71} & {8} &{73} & {72-74} & {7} & {76} & {75-77} & {3} & {79} & {78-80} & {1}\ \end{array}$

Using the frequency distribution, I found the mean height to be 70.2903 with a standard deviation of 3.5795

Step-by-step explanation:

Given

See attachment for class

Solving (a): Fill the midpoint of each class.

Midpoint (M) is calculated as:

$M = \frac{1}{2}(Lower + Upper)$

Where

$Lower \to$ Lower class interval

$Upper \to$ Upper class interval

So, we have:

Class 63-65:

$M = \frac{1}{2}(63 + 65) = 64$

Class 66 - 68:

$M = \frac{1}{2}(66 + 68) = 67$

When the computation is completed, the frequency distribution will be:

Solving (b): Mean and standard deviation using 1-VarStats

Using 1-VarStats, the solution is:

$\bar x = 70.2903$

$\sigma = 3.5795$

<em>See attachment for result of 1-VarStats</em>

8 0

3 years ago

80 - [50 - {20 ÷ 2 – (16 - 2÷ 2) ÷ 3}]

trapecia [35]

Answer:

Step-by-step explanation:

We have to solve the problems in the parenthesis first.

(16-2÷2)= (16-1)=(15)

20÷2-15÷3

(20÷2)-(15÷3)

10-5=5

50-5= 45

80-45= 35

Hope this helps!

6 0

3 years ago

I need help with this

djyliett [7]

Answer:I don't know this one.

Step-by-step explanation:

7 0

3 years ago

An unopened cereal box contains `15/28` cubic foot of cereal. If the box is full, and the length and height of the box are `5/7`

babymother [125]

Answer:

A. `1/2` foot

Step-by-step explanation:

The computation of the width of the box is shown below:

15 ÷ 28 = (5 ÷ 7)(1 1 ÷ 2)(width)

15 ÷ 28 = (5 ÷ 7)(3 ÷ 2)width

15 ÷ 28 = (15 ÷ 14)width

(15 ÷ 28) ÷ (15 ÷ 14) = width

(15 ÷ 28) × (14 ÷ 15) = width

w = 14 ÷ 28

= 1 ÷ 2 ft

7 0

3 years ago

Read 2 more answers