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likoan [24]
3 years ago
8

Solve by the addition method: 2x-5y=18 ,3x+4y=4

Mathematics
1 answer:
alexgriva [62]3 years ago
8 0
2 x - 5 y = 18  / * 4
3 x + 4 y = 4   / * 5  ( we will use the addition method )
--------------------------
 8 x - 20 y = 72
+
15 x + 20 y = 20
----------------------- 
23 x = 92
x = 92 : 23
x = 4
8 - 5 y = 18
- 5 y = 18 - 8
- 5 y = 10
y = 10  : ( - 5 ) 
y = - 2
Answer:
( x, y ) = ( 4, - 2 ) 
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Consider the following equations and name the property of equality used to solve for the variable.
Viktor [21]

9514 1404 393

Answer:

  A. subtraction

  B. division

  C. multiplication

  D. addition

Step-by-step explanation:

Observe what is done to the variable. Choose the operation that turns the unwanted value into the appropriate identity element.

A. 3.75 is added. To make that value be 0, we subtract 3.75.

B. -3 is multiplied. To make that value be 1, we divide by -3.

C. m is divided by 5. To make that 1/5 multiplier be 1, we multiply by 5.

D. 4 is subtracted. To make that value be zero, we add 4.

_____

<em>Additional comment</em>

Since subtraction is the same as addition of the opposite, and division is the same as multiplication by the reciprocal, the only two properties we really need are the <em>addition property</em> and <em>multiplication property</em>. Your grader may disagree.

5 0
3 years ago
If you flip a fair coin 7 times, what is the probability that you will get exactly 4 tails?
andre [41]

Probability that you will get exactly 4 tails, if you flip a fair coin 7 times is: \frac{35}{128}

Step-by-step explanation:

We need to find the probability that you will get exactly 4 tails, if you flip a fair coin 7 times.

This is the combination question.

The total combinations will be: 2^7=128

Now, finding number of ways we can get exactly 4 tiles:

We will use the formula:

^nC_k=\frac{n!}{k!(n-k)!}

in our given question, n= 7, k= 4

Putting values:

^nC_k=\frac{n!}{k!(n-k)!}\\^7C_4=\frac{7!}{4!*3!}\\ ^7C_4=\frac{7*6*5*4!}{4!*3!}\\ ^7C_4=\frac{7*6*5}{6}\\ ^7C_4=35

So, Probability that you will get exactly 4 tails, if you flip a fair coin 7 times is: \frac{35}{128}

Keywords: Probability

Learn more about Probability at:

  • brainly.com/question/1637111
  • brainly.com/question/2254182
  • brainly.com/question/2264295

#learnwithBrainly

7 0
2 years ago
I need help with this. I'll mark brainliest to whoever is correct
zaharov [31]

Answer:

As shown in picture, the area is divided into 4 parts: 3 triangles and 1 rectangles.

Total area:

A = smallest triangle + medium triangle + largest triangle + rectangle

   = 2 x 2 x 1/2 + 2 x 6 x 1/2 + 4 x (2 + 2 + 6) x 1/2 + 2 x 2

   = 2 + 6 + 20 + 4

   = 32

Hope this helps!

:)

8 0
2 years ago
3. Sophie and Jackie each have a collection of baseball cards, Jackie has 5 more cards than
IRISSAK [1]

Answer:

Sophie has 12.5 cards

Step-by-step explanation:

Let

x -----> number of cards Sophie has

y -----> number of cards Jackie has

we know that

x+y=30 -----> equation A  

y=x+5 -----> equation B

Solve by substitution

Substitute equation B in equation A and solve for x

x+(x+5)=30

2x=30-5

x=12.5 cards

Note I assume the problem was invented without taking into account the result, because the amount of cards should be a whole number

5 0
2 years ago
Blake has b baseball cards. His aunt gave him more cards, increasing his total number of cards by 25%. Which expression represen
Vera_Pavlovna [14]
.25b+ b is the answer to ur question
6 0
3 years ago
Read 2 more answers
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