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1 year ago

Thu gọn biểu thức : (x-5)(x+5)-(x+1)^2

Mathematics

1 answer:

Kipish [7]1 year ago

5 0

$(x-5)(x+5)-(x+1)^2\\=x^2 -25-(x^2+2x +1)\\=x^2 -25-x^2-2x -1\\=-2x-26$

ANSWER: -2x -26

Ok done. Thank to me :3

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A bacteria culture starts with 1000 bacteria and the number doubles every 40 minutes. (a) find a formula for the number of bacte

vfiekz [6]

The formula for the number of bacteria at time t is 1000 x (2^t).

The number of bacteria after one hour is 2828

The number of minutes for there to be 50,000 bacteria is 324 minutes.

<h3>What is the number of bacteria after 1 hour?
</h3>

The exponential function that can be used to determine the number of bacteria with the passage of time is:

initial population x (rate of increase)^t

1000 x (2^t).

Population after 1 hour : 1000 x 2^(60/40) = 2828

Time when there would be 50,000 bacteria : In(FV / PV) / r

Where:

FV = future bacteria population = 50,000
PV = present bacteria population = 1000
r = rate of increase = 100%

In (50,000 / 1000)

In 50 / 1 = 3.91 hours x 60 = 324 minutes

To learn more about exponential functions, please check: brainly.com/question/26331578

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5 0

2 years ago

If 8% of all cell phones are defective, and you have a random sample group of 100 Samsung Galaxy Vills,

Sati [7]

Answer:

Mean = 8

Variance = 7.36

Standard Deviation = 2.7129

Step-by-step explanation:

This is a binomial distribution with parameters, n and p.

Where

n is sample size (given as 100)

p is the probability of success, or probability of defective (given as 8% or 0.08)

The mean, variance, standard deviation formula for binomial distribution is shown below:

Mean = $np$

Variance = $npq$

Standard Deviation = $\sqrt{npq}$

Where q would be probability of failure, or "1 - p"

Thus,

n = 100

p = 0.08

q = 1 - 0.08 = 0.92

SO, we have:

Mean = $np=100*0.08=8$

Variance = $npq=100*0.08*0.92 = 7.36$

Standard Deviation = $\sqrt{npq}=\sqrt{7.36}=2.7129$

5 0

3 years ago

Pls help with these two math questions

-BARSIC- [3]

Number 18 is D) (3+8m)-7

Number 19 is:

1) z>1

2) z>-1

3) z<1

4) z<-1

4 0

4 years ago

Read 2 more answers

How do I find the mass of 250.0mL

kupik [55]

Answer:

mass = density · volume

Step-by-step explanation:

To find the mass of a given volume, multiply your given volume by the <em>density</em>. Often, density is given in grams per cubic centimeter. 1 cubic centimeter is the same as 1 milliliter.

4 0

4 years ago

Please help! Thanks in advance.

alukav5142 [94]

In this problem, we need to plug in the given x values for $f(x)=0$ and find a and b.

When we plug in 1, we get: $2 \times {1}^{4} - 5 \times {1}^{3} - 14 \times {1}^{2} + a \times 1 + b = 0$

Simplify:
$2 - 5 - 14 + a + b = 0$
$- 17 + a + b = 0$
$a + b = 17$

We got our first statement about the values of the variables. If we find one more we can find those 2 variables.

We have another given root: 4.

Plug it in:
$2 \times {4}^{4} - 5 \times {4}^{3} - 14 \times {4}^{2} + a \times 4 + b = 0$
$512 - 320 - 224 + 4a + b = 0$
$- 32 + 4a + b = 0$
$4a + b = 32$

Now we have our second one. We can combine them:
$a + b = 17 \\ 4a + b = 32$

I use elimination method which is easier here.

Multiply the top equation by -1: $- a - b = - 17 \\ 4a + b = 32$

Add them up:
$3a = 15$

Simplify:
$a = 5$

Now we have a, we can plug in one of those equations to find b:
$5 + b = 17$
$b = 17 - 5$
$b = 12$

So, the answers are $a=5$ and $b=12$ .

6 0

4 years ago