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lord [1]
3 years ago
6

What is (1-7x)(1+9x)

Mathematics
2 answers:
Vikentia [17]3 years ago
7 0

Answer:

1+2x-63x^2

Step-by-step explanation:

factor 1(1+9x)=1+9X

-7x(1+9x)=-7x-63x^2

add 1+9x-7x-63x2

Sveta_85 [38]3 years ago
5 0

ANSWER

(1-7x)(1+9x) =-  63 {x}^{2} + 2x + 1

EXPLANATION

The given product is (1-7x)(1+9x).

Expand using the distributive property.

(1-7x)(1+9x) = 1(1 + 9x) - 7x(1 + 9x)

(1-7x)(1+9x) = 1 + 9x - 7x -  63 {x}^{2}

Simplify to obtain:

(1-7x)(1+9x) = 1 + 2x -  63 {x}^{2}

You can rewrite in standard form to get,

(1-7x)(1+9x) =-  63 {x}^{2} + 2x + 1

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The number of girls in three-child families in a certain geographic area is investigated. Of 212 families with exactly three chi
Sati [7]

Answer:

p = 0.513

Step-by-step explanation:

There are 212 families with exactly 3 children. So in all, there are 212*3 = 636 children.

Of those,

The number of girls is:

81 + 76*2 + 31*3 = 326

That is, 326 girls out of 636 children.

Then

p = \frac{326}{636} = 0.513

3 0
4 years ago
Find the gcf of 72 and 80
Rainbow [258]
One way to I solve this is by listing all the ways it can be multiplied by:
72: 1*72, 2*36, 3*24, 4*18, 6*12, 8*9.
80: 1*80, 2*40, 4*20, 5*16, 8*10.
Group the factors that they have in common.
Which are 1, 2, 4, and 8.
After that, find the greatest common factor that they both share.

Answer: 8
3 0
3 years ago
Susan and John are buying cold drinks for a neighborhood picnic. Each person is
givi [52]

Answer:

Susan has suggested a correct method to calculate the amount of money

Step-by-step explanation:

Here we must check what each person is calculating. First, we consider Susan's method. She has suggested that we multiply the cost per soda, that is dollars/soda by the number of sodas required, we get the total cost.

Assuming that 18 sodas are required and each costs $0.20, the total cost according to Susan is $3.60.

John suggests we divide the cost of a 12 pack of soda by the number of sodas required. Considering a 12 pack of soda costs $12 and the same amount of sodas, 18, are required, we get that each soda costs $0.66.

Looking at these answers, we see that Susan has suggested a correct method to calculate the amount of money needed to buy a number of sodas. John has suggested the amount each person would have to contribute if everyone at the party was trying to buy a 12-pack of soda; regardless of whether more or less than a 12-pack is required.

4 0
3 years ago
When the outliers are removed, how does the mean change? (2 points) dot plot with 1 on 50, 1 on 76, 1 on 78, 2 on 79, 1 on 80, 1
777dan777 [17]

Answer:

Answer: The mean increases by 3

Step-by-step explanation:

The original data set is 

{50, 76, 78, 79, 79, 80, 81, 82, 82, 83}

The outlier is 50 because it is not near the group of values from 76 to 83 which is where the main cluster is.

The original mean is M = (50+76+78+79+79+80+81+82+82+83)/10 = 77

If we take out the outlier 50, the new mean is N = (76+78+79+79+80+81+82+82+83)/9 = 80

So in summary so far

old mean = M = 77

new mean = N = 80

The difference in values is N-M = 80-77 = 3

So that's why the mean increases by 3

8 0
3 years ago
The quality control manager at a computer manufacturing company believes that the mean life of a computer is 120 months, with a
IrinaK [193]

Answer:

P(X<118.81)=0.0803

Step-by-step explanation:

Assuming the distribution for the mean life is approximately normal, with mean 120 months and variance 64 months^2, we can calculate the parameters for a sampling distribution with sample size = 89 computers.

The sampling distribution mean will be equal to the mean for a single computer:

\mu_{89}=\mu=120

The standard deviation will be adjusted by the sample size as:

\sigma_{89}=\sqrt{\sigma^2/n}=\sqrt{64/89}=\sqrt{0.719}=0.848

With these parameters, we can calculate the z-score for X=118.81.

z=\dfrac{X-\mu}{\sigma}=\dfrac{118.81-120}{0.848}=\dfrac{-1.19}{0.848}=-1.403

Then, the probability that the mean of a sample of 89 computers is less than 118.81 months is:

P(X

7 0
3 years ago
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