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3 years ago

Solve using elimination. 3x − 5y = 18 -10x + 5y = 10

Mathematics

2 answers:

olga55 [171]3 years ago

5 0

3x - 5y = 18 over

-10x + 5y = 10

Add them because the 5y's have the right symbols for us to add

-7x = 28

Divide

x = -4

Now you can plug in -4 for x in one equation, I would use the first equation!

3(-4) - 5y = 18

-12 - 5y = 18

Add 12

-5y = 30

Divide

y = -6

Your solutions are going to be:

x = -4

y = -6

To check your work plug x and y into one equation:

3(-4) - 5(-6) = 18

-12 + 30 = 18

18 = 18

Since 18 does equal 18 you know that your solution's work!

GalinKa [24]3 years ago

4 0

Yes that is the right answer

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3 years ago

A theater has 56 rows of seats. If there are 13 seats in the first row, 18 in the 2nd row, 23 in the 3rd row. How many seats are

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Answer:

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Step-by-step explanation:

According to the Question,

Given, A theater has 56 rows of seats. If there are 13 seats in the first row, 18 in the 2nd row, 23 in the 3rd row.

We have a number sequence 13, 18, 23, ...

We can say that this is an arithmetic sequence because of the common difference 'd', is equal to 5, and the first term 'a1' is equal to 13.

The formula for the sum of an arithmetic sequence with n terms is given is $S_n= \frac{n}{2} [2a_1+(n-1)d]S$ .

Substitute the given values into the equation to solve for the sum of the 56 rows of seats.

$S_56= \frac{56}{2}[2(13)+(56-1)(5)]\\S_{56}=28\left[26+275\right]\\S_{56}=28\left[301\right]\\S_{56}=8428$

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