amanda solve the folling problem below. did she solve it correctly? If not, what was her error? how can you check to be sure?

Plz hurry
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Answer:

(x-5)(x+4) = 0

Step-by-step explanation:

We are given the quadratic equation x²-x=20

And we want to factor it, meaning that we want to split it apart, usually to make it easier to solve.

First, let's subtract 20 from both sides, as when all 3 terms of a quadratic equation are on the same side, it makes it a lot easier to solve.

x² - x = 20

    -20  -20

_______________

x² - x - 20 = 0

Now, we can get on to factoring.

In a quadratic equation, written as ax² + bx + c = 0 (like in here), b (the coefficient in front of just x, not x²) is equal to the sum of two numbers, while c is the product of the same two numbers.

The coefficient in front of x (b) is -1, and c is equal to -20.

Now think: which two numbers add up to -1, and multiply to equal -20?

Those numbers are -5 and 4.

Now, to factor a quadratic, we split it up into 2 binomials multiplied by each other, and each binomial is x + one of the numbers we found above. It looks like this: (x+1)(x+2). Remember that this only affects the left side; the right side stays the same.

In this case, we have -5 and 4, which will take the place of 1 and 2 in the example above.

Therefore, the factored form of x² - x - 20 = 0 is (x-5)(x+4) = 0.

Answer:

18.

Step-by-step explanation:

2 = 2

9 = 3*3

So, the LCD = 2*3*3     (no duplicates in the 2 lists).

= 18.

Step-by-step explanation:

23 + 10 - 2 + 14 + 2

33 - 2 + 16

31 + 16 = 47

The numerical expression for the verbal expression is 18 ÷ (2+7).

Given,

Verbal expression = Eighteen divide by the sum of two and seven

we know that ,

We can write any  verbal expression  to numerical expression by using playing with numbers.

Playing with numbers:

Playing with numbers involves activities like arranging the numbers, understanding , finding out whether a given number is a factor of another number or a multiple of another number, and understanding the properties of factors and multiples

Now, According to question

Eighteen divided by the sum of two and seven

18÷(2+7)

Therefore,

The numerical expression is 18÷(2+7).

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Answer:

II. 48.6×0.1

III. 0.0486×100

Step-by-step explanation:

48.6×0.1 = 4.86

0.0486×100 = 4.86

Answer:

ll and lll are equal.

Step-by-step explanation:

4.86x0.01 = 0.0486

48.6 x 0.1 = 4.86

0.0485 x 100 = 4.86

48.6 x 10 = 486

Answer:

No solution

Step-by-step explanation:

Simplify and combine like terms

3x - 3 = 3x - 5

Subtract 3x on both sides.

-3=-5

No solution

Answer:

-2

Step-by-step explanation:

The number of mezzanine tickets sold = 540

Total number of tickets sold = 910

Total number of tickets sold is the sum of the number of regular seats and the number of the mezzanine seats sold.

Let 'x' be the number of regular seats and 'y' be the number of mezzanine seats.

Then x + y = 910     ----------(1)

Cost of a regular seat = $ 18.50

So cost of x regular seats = 18.50x dollars

Cost of a mezzanine seat = $ 16.25

So cost of y mezzanine seats = 16.25y

Total amount of money she got by selling tickets = $ 15620

Therefore, 18.5x + 16.25y = 15620 ----------------(2)

Solve equations (1) and (2) for x and y.

Multiplying (1) with 18.5 throughout,

18.5x + 18.5y = 16835 ---------------(3)

Subtracting (2) from above equation (3), we get,

(18.5 - 16.25)y = 16835 - 15620

⇒ 2.25y = 1215

⇒ y = 1215/2.25

⇒ y = 540

Hence 540 mezzanine tickets were sold.

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Answer: B

Step-by-step explanation:

4 times 3 times 3 times 3 times 3=108

Answer:

A. 39

Step-by-step explanation:

Given:

Length of a pyramid (lpy ) = 4 cm

Width of a pyramid (wpy ) = 3 cm

Height of a pyramid (hpy ) = 3 cm

It is given that the rectangular pyramid fits exactly on top of the prism, the length and width of the prism are the same for the base of the pyramid.

So, Length of a prism (lpr) =3 cm, width of a prism (wpr) = 3cm and height of a prism (hpr) = 3 cm

Volume of Prism (Vpr) = lpr × wpr × hpr

⇒ Vpr = 3 cm × 3 cm × 3 cm

⇒ Vpr = 27 cm³ ....(eq 1)

Volume of Rectangular Pyramid Vpy

= (lpy × wpy × hpy ) / 3

⇒ Vpy = (4 × 3 × 3) ÷ 3

⇒ Vpy = 12 cm³ ....(eq 2)

From 1 and 2, Volume of composite space,

Volume of composite space = Volume of prism + Volume of Pyramid

⇒ V = 27 cm³ + 12 cm³ = 39 cm³

⇒ V = 39cm³

Step-by-step explanation:

the domain is the interval or set of all valid x (input) values.

the range is the interval or set of all valid y (function result) values.

so, we see here, x goes from -2 to +2.

and y stays between -5 and -1.

the hole point at (-2, -1) means the point itself is not included. the full point (2, -1) means the point itself is included.

the domain is

-2 < x <= +2

"-2 < x" because (-2, -1) is not included.

"x <= +2" because (2, -1) is included.

the range is

-5 <= y <= -1

"y <= -1" because for the included point (2, -1) y can reach -1, even though (-2, -1) is excluded.

Answer:

Here SOLUTION: −5x + 4y = 20. 10x − 8y = −40.

Step-by-step explanation:

First, solve the first equation for y. Then, substitute for y in the second equation. This equation is an identity.

Step-by-step explanation:

i think it is 35 but im probaly wrong

Answer: y = 5x/4 - 13

Step-by-step explanation:

y=mx+b

7=5/4 *16+b

7=5*16/4 +b

7=80/4+b

7=20+b

b=-13

y = 5x/4 - 13

When Jake rolls the same dice 720 times, the number of 5s will be 135.

It should be noted that the frequency for 5 is 75 out of 400. This will be:

= 75 / 400

= 3/ 16

Therefore, when Jake rolls the same dice 720 times, the number of 5s will be:

= 3/16 × 720

= 135

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Answer:11.25

Step-by-step explanation:because we have to find out how many gallons we have in one hour so you divide both sides by 4

4/4 is 1 hour

3/4 is 0.75 gallons then you have to multiply both sides by 15

1 hour times 15 is 15 hours

the 0.75 x 15 is 11.25

so the answer is 11.25 gallons that she uses in 15 hours

hope this helps

The required probability is  [tex]\frac{1}{10}[/tex].

This problem is related to probability.

First we have to calculate the number of outcomes and then the number of favorable outcomes.

In this case the numbers are from 1 to 150.

First we have to find the numbers which are perfect square between 1 to 150= {1,4,9,16,25,36,49,64,81,100,121,144}

Now we have to find the numbers which are perfect cube other than those which came in square={8,27,125}

Here the number of favorable outcome is 150 minus number of elements in set of perfect square and perfect cube.

Now the probability of the required problem is = [tex]\frac{15}{150}[/tex]

                                                                         = [tex]\frac{1}{10}[/tex]

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Answer:

1 1/6

Step-by-step explanation:

1 2/3 - 1/2 =

1 2/3 = 1 4/6

1/2 = 3/6

1 4/6 - 3/6 =

1 1/6

Answer:

$3

Step-by-step explanation:

Divide 6 from 18 to find the cost per shirt.

18/6=3

3 dollars per shirt.

Hope this helps!

Please mark as brainliest if correct!

Answer:

five thousand clay to school

Answer:

These are dividend, divisor, quotient and remainder.

Step-by-step explanation:

Determine the first digit or set of digits your divisor will go into at least once.

Determine the maximum number of times your divisor will go into the said digit or digits.

Place the answer over the corresponding digit. For multiple digits, place it over the last digit.

Multiply the answer from above by your dividend.

Place the result under your dividend starting from the left most digit.

Subtract the result from your dividend. Only subtract the digits that line up. For instance, if you have a five digit dividend, but the result is only two digits, only subtract using the first two digits of your dividend.

Bring down the next digit of your dividend beside the result.

Repeat the process using the new set of digits. Each time, bring down the next digit of your dividend.

Answer:

Your answer would be 3.075.

Step-by-step explanation:

15 - 6.8 = 8.2

8.2 - 5 1/8 = 3.075

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

Hope this helps!

Have a great day and God bless! :)

40 black socks should be added to the suitcase( i.e., option h )

Let's take x = black socks added by Jamal

Based on the given condition, we have

[tex]\frac{10}{10 + x}[/tex] = 1/5

Here x ≠ -10

Because to define the fraction, the denominator should not be 0.

Now we need to find the value of x,

[tex]\frac{10}{10 + x}[/tex] = 1/5

50 = 10 + x

x = 40

Therefore 40 socks should Jamal add to the suitcase.

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Answer:

D. 140. ....,.....

Step-by-step explanation:

160-20=140

Using the concept of ratio the number of cups of chips Charlie needs can be found out.

A ratio in mathematics shows how many times one number is contained in another. The ratio symbol is represented by a colon (:).A ratio is still valid if all of the quantities are multiplied by the same number. By dividing each quantity by the sum of all the numbers' common factors, ratios can be lowered (much like fractions are). The simplest version of a fraction is one in which the ratio's numbers are the smallest feasible integers.

Amount of dip required by the recipe be 'a' =[tex]1\frac{1}{4}[/tex] cups=[tex]\frac{5}{4}[/tex]cups

Amount of chips required by the recipe be 'b'= [tex]\frac{1}{5}[/tex]cups

Amount of chips to be used be 'c'= 1 cup

Number of cups of chips Charlie needs

=[tex]\frac{c*a}{b}[/tex]

=[tex]\frac{1*\frac{5}{4} }{\frac{1}{5} }[/tex]

=[tex]\frac{5*5}{4}[/tex]

=[tex]\frac{25}{4}[/tex] cups

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The width of rectangular garden comes out to be 20 feet .

Let the width be x feet .

Therefore , length is ( x + 32 ) feet .

Formula for perimeter of a rectangle :

perimeter = 2 ( length + breadth )

By substituting the values in the formula above , the equation becomes ,

2 ( x + x + 32 ) = 144

2 x + 32 = 144 / 2

     2 x = 40

        x = 20

Hence , width = 20 feet , length = 52 feet .

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Answer:

32in2

Step-by-step explanation:

The number of people who like red color is 255 students when 85% said their favorite color was red.

Percentage, a relative value indicating hundredth parts of any quantity. One percent (symbolized 1%) is a hundredth part; thus, 100 percent represents the entirety and 200 percent specifies twice the given quantity. percentage.

Given:

Total students =300

85% said their favorite color was red.

So, students whose favorite color was red

=85/100 *300

=85*3

= 255 students.

Hence, 255 students whose favorite color was red

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Answer: $100

Step-by-step explanation:

3,000 divided by 30 is 100

Answer: 100

Step-by-step explanation: divide 3,000 by 30

Answer: A. x=8

Step-by-step explanation:

0.4(5x-12)+0.5x=15.2

(0.4)(5x)-(0.4)(12)+0.5x=15.2

2x-4.8+0.5x=15.2

2.5x-4.8=15.2

2,5x-4.8+4.8=15.2+4.8

2,5x=20

(2.5)(x)=(2.5)(8)

Divide both parts of the equation by 2.5:

x=8