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2 years ago

Solve the equation. Check for extraneous solutions. 2|7−7x|=2x+4

Mathematics

1 answer:

Vesna [10]2 years ago

5 0

2|7 − 7x| = 2x + 4

|7 - 7x| = x + 2

7 - 7x = x + 2 or 7 - 7x = -(x + 2)

-8x = -5 or 7 - 7x = -x - 2

x = 5/8 or -6x = -9

x = 5/8 or x = 9/6

x = 5/8 or x = 3/2

To check for extraneous solutions, we check both solutions in the original equation.

Check solution 5/8:

2|7 - 7x| = 2x + 4

|7 - 7x| = x + 2

|7 - 7 * 5/8| = 5/8 + 2

|56/8 - 35/8| = 5/8 + 16/8

21/8 = 21/8

Solution x = 5/8 works.

Check solution 3/2:

2|7 - 7x| = 2x + 4

|7 - 7x| = x + 2

|7 - 7 * 3/2| = 3/2 + 2

|14/2 - 21/2| = 3/2 + 4/2

|-7/2| = 7/2

7/2 = 7/2

Solution 3/2 also works.

Answer: x = 5/8 or x = 3/2

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PSYCHO15rus [73]

The number of books sold is 473.

Step-by-step explanation:

The original cost of each book = $0.64
The selling price of each book = $0.75

The difference between the original price and selling price of the book gives the profit per book.

The profit of one book = Selling price - Original price

Let,

The total number of books be 'x'.
The number of books sold be 'y'.
The unsold books is 100.
The total profit is -12 because it was gone to a loss of $12.

Therefore, the equation is formed as

total Profit = 0.75y - 0.64x

⇒ 0.75y - 0.64x = -12 --------(1)

Total books = sold books + unsold books

x = y + 100

⇒ x-y = 100 -------(2)

Substitute x= 100+y in the eq(1),

0.75y - 0.64(100+y) = -12

0.75y - 64 -0.64y = -12

0.11y = -12 +64

y = 52 / 0.11

y = 472.7

y ≅ 473

The number of book sold is 473 books.

The total number of books is (100+473) = 573 books.

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3 years ago

you are using division to determine how much whole wheat flour to use in a bread recipe.is an estimated answer good enough? plea

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2 years ago

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Rus_ich [418]

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3 years ago

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nikitadnepr [17]

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2 years ago

An instructor wants to write a test with 25 questions where each question is worth 3, 4, or 5 points based on difficulty. He wan

irakobra [83]

ANSWER

Find out the how many 3, 4, and 5 point questions could there be.

To proof

Let us assume that the 3 points based question be = x

Let us assume that the 4 points based question be = y

Let us assume that the 5 points based question be = z

As given

An instructor wants to write a test with 25 questions

than the equation become in the form

x + y + z = 25

he quiz to be worth a total of 100 points.

than the equation is becomes

3x + 4y + 5z =100

As given

He wants the number of 3-point questions to be 4 less than the number of 4-point questions

x = y -4

Than the three equation are

x + y + z = 25 ,3x + 4y + 5z =100 and x = y -4

put x = y -4 in the x + y + z = 25 ,3x + 4y + 5z =100

than

2y + z = 29, 7y +5z= 112

multiply 2y + z = 29 by 5 and subtracted 7y +5z= 112

10 y -7y + 5y -5y = 145 -112

3y = 33

$y = \frac{33}{3}$

y =11

put in the x = y -4

x = 11-4

x= 7

put the value of x ,y in the x + y + z = 25

7 + 11 +z =25

18 +z = 25

z = 25 -18

z=7

therefore

numbers of the 3 point question be = 7

numbers of the 4 point question be = 11

numbers of the 5 point question be = 7

Hence proved

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