Alexey wrote '1*2*3*... 9 = 21' on the board, inserting a plus or minus signs in place of each little star. Sasha changed some of these signs to their opposites so that the result he got was 20. Prove that one of the boys made a mistake.​

Answer:

Solution given

4x+2=-13

subtract each term by 2

4x+2-2=-13-2

divide both side by 4

4x/4=-15/4

we get

x=-15/4

is a required answer.

Let's solve:

[tex]4x+2=−13[/tex]

Step 1: Subtract 2 from both sides.

[tex]4x+2−2=−13−2 \\ 4x = - 15[/tex]

Step 2: Divide both sides by 4.

[tex] \frac{4x}{4} = \frac{ - 15}{4} [/tex]

Answer:

[tex] \frac{ - 15}{4} [/tex]

Answer:

X = 11

Step-by-step explanation:

3^(x-7) = 81

Find what exponent makes three into 81

The answer: x = 11

Answer:

x = 11

Step-by-step explanation:

Given

[tex]3^{x-7}[/tex] + 4 = 85 ( subtract 4 from both sides

[tex]3^{x-7}[/tex] = 81

[tex]3^{x-7}[/tex] = [tex]3^{4}[/tex]

Since the bases on both sides are equal, both 3 then equate the exponents

x - 7 = 4 ( add 7 to both sides )

x = 11

Answer:

$66.00

Step-by-step explanation:

first we need multiply :D I will use the formula I =prt

principal= $500

rate=3.3%

time= 4 years

but we need to convert the percent, 3.3%, to a decimal

3.3%=0.033 or .033

now we multiply !

500 × 0.033 × 4 = 66 = $66.00

Answer

15.8

Step-by-step explanation:

Answer: Choice D

[tex]\frac{9\sqrt{2}}{2}[/tex]

=============================================

Explanation:

We have a 45-45-90 triangle. If x is the leg length, then y = x*sqrt(2) is the hypotenuse.

Solving for y gets us [tex]x= \frac{y}{\sqrt{2}} = \frac{y\sqrt{2}}{2}[/tex]

In this case, y = 9 is the hypotenuse which then leads to choice D.

------------

Another way to find the answer is to use the pythagorean theorem

a = x and b = x are the two congruent legs

c = 9 is the hypotenuse

Solving a^2+b^2 = c^2, aka x^2+x^2 = 9^2, will lead to [tex]x = \frac{9\sqrt{2}}{2}[/tex]

Answer:

19329.84

Step-by-step explanation:

3.14×18 which is squared so it 324×19

3.14×324×19= answer

Answer:

$17.50 is how much Priyah makes per hour

Probability  that the two numbers are multiples of 3 after replacing first

It is a branch of mathematics that deals with the occurrence of a random event.

The odd integers from11 to 22 are

11,13,15,17,19,21

So there are 6 events

Out of these 6 numbers, 2 numbers (15,21) are multiples of 3.

One number out of these 2 numbers can be chosen in 2 ways.

Therefore, favourable number of elementary events = 2.

Required probability =2/6=1/3

Hence 1/3 is the probability  that the two numbers are multiples of 3 after replacing first

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Answer:

y=2x+4

Step-by-step explanation:

2x is the gradient and the y intercept is 4 so we just put them into the equation y=mx+c

Answer:

A

Step-by-step explanation:

The best way to prove the answer is to equate the two equation and solve for the x-coordinate..however in these equation the x value is zero so the y value will alternatively be zero hence there lines consist of no points of intersection

THE CORRECT ANSWER IS 57 CM³!

Answer:

consistent.

Step-by-step explanation:

if lines cross they're consistent. If they dont they're inconsistent and if they overlap completely they're equivalent

Answer:

80miles

Step-by-step explanation:

400=L

L[tex]\sqrt{400[/tex]

=20

to find p

4L

4(20=80

Answer:

[tex] \frac{x}{ {a}^{2} } [/tex]

Step-by-step explanation:

Matthhh

Answer:

x/a^2

Step-by-step explanation: Please tell me if this is right or wrong

The number that best describes the range of the data in the box-and-whisker plot is 15.

A box plot is used to study the distribution and level of a set of scores the scores are distributed into 4 groups. Each group has a value of 25%. The box plot consists of two lines and a box. the two lines are known as whiskers. the whiskers represents the minimum and maximum values.

Range = maximum value - maximum value  

20 - 5  = 15

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Answer:

To solve for x,  I would use Cosine.

This is because cosine holds the ratio of adjacent/hypotenuse. Based on the diagram, we can see that HYPOTENUSE = x, so we are solving for x. We know the angle, is 17 degrees. Lastly, we know the triangle leg ADJACENT to the angle is 10 units long. So we would use cosine, implementing the ratio adjacent/hypotenuse. Solving this, we would use cos(17)=10/x. Then our goal is to isolate x, so cos(17)=10/x becomes cos(17)*x=10, we are still trying to isolate x, so, x=10/cos(17). Therefore, our answer  x = 10.457 units. cosine would be the best way to go.

Step-by-step explanation:

Answer:

Step-by-step explanation:

I got 408.33. dont know how to help you out

Answer:

a common denominator

Step-by-step explanation:

Answer:

No.

Step-by-step explanation:

3.3 is bigger than 3 by .3: )

Answer:

no.

3.3 > 3

Step-by-step explanation:

15........hope it helps

Answer:

cool

Step-by-step explanation:

ok

Answer:

The interval that would represent weights of the middle 95% of all oranges from this orchard is from 5 oz to 7 oz.

Step-by-step explanation:

The Empirical Rule states that, for a normally distributed random variable:

68% of the measures are within 1 standard deviation of the mean.

95% of the measures are within 2 standard deviation of the mean.

99.7% of the measures are within 3 standard deviations of the mean.

In this problem, we have that:

Mean = 6

Standard deviation = 0.5

Middle 95% of weights:

By the Empirical Rule, within 2 standard deviations of the mean.

6 - 2*0.5 = 5

6 + 2*0.5 = 7

The interval that would represent weights of the middle 95% of all oranges from this orchard is from 5 oz to 7 oz.

Answer:

3/8^3

Step-by-step explanation:

the exponent is 3

Answer:

(3/8)^3

3^3 * 2^-9

Step-by-step explanation:

3/8 * 3/8 * 3/8 = (3/8)^3

= 3^3 * (1/8)^3 = 3^3 * (2^-3)^3 = 3^3 * 2^-9

Answer:

To find a relative frequency you need to divide the total number of x in the frequency to the total number. This can be represented as a fraction, decimal,  or percent.

Step-by-step explanation:

For example,

The ball landed 3 times out of 40.

3/40 = 7.5%

Step-by-step explanation:

To find the relative frequencies, divide each frequency by the total number of students in the sample–in this case, 20. Relative frequencies can be written as fractions, percents, or decimals. Cumulative relative frequency is the accumulation of the previous relative frequencies.

Example: Your team has won 9 games from a total of 12 games played: the Frequency of winning is 9. the Relative Frequency of winning is 9/12 = 75%

Answer:

past participle

Step-by-step explanation:

all of the other ones are correct

Answer:

We can conclude that the room temperature on Saturday was 24°C

Step-by-step explanation:

For a set of N values:

{x₁, x₂, ..., xₙ}

The mean of the set is calculated as:

[tex]M = \frac{x_1 + x_2 + ... + x_n}{N}[/tex]

In this case, our set is the temperature of 7 days (so we have 7 elements)

{T₁, T₂, T₃, T₄, T₅, T₆, T₇}

Such that:

T₆ = temperature on Saturday

T₇ = temperature on Sunday.

We know that:

"The mean room temperature from Monday to Saturday is 25°C"

Then:

[tex]\frac{T_1 + T_2 + T_3 + T_4 + T_5 + T_6}{6} = 25 C[/tex]

"the mean room temperature of Saturday and Sunday is 28°C"

[tex]\frac{T_6 + T_7}{2} = 28C[/tex]

"The mean room temperature from Monday to Sunday is 26°C"

[tex]\frac{T_1 + T_2 + T_3 + T_4 + T_5 + T_6 + T_7}{7} = 26 C[/tex]

So we have 3 equations.

Let's rewrite:

T₁ + T₂ + T₃ + T₄ + T₅ = A

Then we can rewrite our equations as:

[tex]\frac{A+ T_6}{6} = 25 C[/tex]

[tex]\frac{T_6 + T_7}{2} = 28C[/tex]

[tex]\frac{A + T_6 + T_7}{7} = 26 C[/tex]

Removing the "Celcius" and multiplying in the 3 equations by the denominator on both sides, we get:

A + T₆ = 6*25

T₆ + T₇ = 2*28

A + T₆ + T₇ = 7*26

We now need to solve that system for T₆

The first step is to isolate one of the variables in one of the equations, (because we want to solve this for T₆ , let's not isolate that one). Let's isolate A in the first one:

A = 6*25 -  T₆

A = 150 -  T₆

Now we can replace this on the other two equations:

T₆ + T₇ = 2*28

(150 -  T₆ ) + T₆ + T₇ = 7*26

Now, let's isolate T₇  in the top equation to get:

T₇  = 2*28 - T₆

T₇  = 56 - T₆

Now we can replace this in the last equation to get:

(150 -  T₆ ) + T₆ + (56 - T₆)  = 7*26

Now, we can solve this for T₆

150 - T₆ + T₆ + 56 - T₆ = 182

-T₆ = 182 - 150 - 56

-T₆ = -24

T₆ = 24

We can conclude that the room temperature on Saturday was 24°C

Answer:

59.50

Step-by-step explanation:

Answer:

1. 8.9

2. 14.5

3. 10.3

4. 18.8

5. 8.0

6. 15.0

(All to the nearest tenth)

The code is the sum of all missing sides

So adding all

=75.5

Answer:

t > -7

Step-by-step explanation:

8t - 2 - 9t < 5

Combine like terms

- 2 - t < 5

Add 2 to each side

-2-t+2 < 5+2

-t <7

Multiply each side by -1, remembering to flip the inequality

t > -7