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ira [324]
3 years ago
12

Solve the following system by the elimination method. Check the solution. 5x−5 = −7y, 3x+2y = - 8

Mathematics
1 answer:
torisob [31]3 years ago
4 0
5x-5=-7y
3x+2y=-8

First, you need to rearrange the first equation so it is in the same format as the second one.
5x-5=-7y
Add 5 to both sides
5x-5+5=-7y+5
Add 7y to both sides
5x+7y=-7y+7y+5
So you have 5x+7y=5

Now you need to multiply that equation by 3
3(5x+7y=5)
15x+21y=15

Multiply the second equation by -5
-5(3x+2y=-8)
-15x-10y=40

Now add them together
15x+21y=15
+(-15x-10y=40)
---------------------
11y=55
y=5

Now plug y=5 into one of the original equations and solve for x.
3x+2(5)=-8 
3x+10=-8
3x=-8-10
3x=-18
x=-6

To check the solution plug them both into the other equation:
5(-6)-5=-7(5)
-30-5=-35
-35=-35

It checks.

Hope that helps.
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Dmitry_Shevchenko [17]

Answer:

15/25

Step-by-step explanation:

So to answer this. lets find the value of 9/15

9/15

=

0.6

Now we know the value of the fraction is 0.6. Now we need to find th4e value of x that makes 15/x=0.6

To find the answer for this, just divide 15 by 0.6:

15/0.6

=

25

<u>So now we know that 15/25 is equal to 9/15</u>

Hope this helps! ;)

5 0
3 years ago
The sum of the first n terms of an arithmetic sequence is n/2(4n + 20).
lesantik [10]

Answer:

(a).

S_{n} =  \frac{n}{2} (4n + 20) \\  \\S _{n - 1} =  \frac{(n - 1)}{2} (4n - 4 + 20) \\  \\ S _{n - 1} =  \frac{(n - 1)}{2} (4n + 16) \\  \\S _{n - 1} = \frac{(n - 1)(4n + 16)}{2}  \\   \\  { \boxed{S _{n - 1} =  {2 {n}^{2} + 6n - 8}}} \\

(b).

from general equation:

S _{n - 1} =  \frac{(n - 1)}{2} (4n + 16)

first term is 4n

common difference:

16 =  \{(n - 1) - 1 \}d \\ 16 = (n - 2)d \\ d =  \frac{16}{n - 2}

8 0
3 years ago
Suppose it takes 180 credits to get a baccalaureate degree. You accumulate credit at the rate of one credit per quarter for each
jonny [76]

The total time to be invested to get a degree would be 630 hours

Total credits required = 180 credits

Number weeks In a quarter = 10 weeks

Number of credit earned per hour = 1 credit

To earn a degree :

Number of credits required per week :

180 / 10 = 18 credits per week

Since, credit is earned at a rate of 1 per hour ; then ;

Number of class hours per week = 18 hours per week.

This means 180 class hours is required.

For every class hour ; 2.5 hours is used for outside class study

Hence, Total outside class study hours will be :

(2.5 hours × 180 hours) = 450 hours

Therefore,

Total hours that would be invested :

(total outside class hours + tt’otal class hours)

(450 + 180) = 630 hours

Learn More : brainly.com/question/18796573

3 0
3 years ago
5. Which expression is a factor of x2 -5x - 6?<br> A<br> B<br> x - 6<br> x-2<br> c<br> x-3<br> 1
noname [10]

Answer:

The answer is B

Step-by-step explanation:

6 0
3 years ago
Janet is trying to prove that the sum of the measures of the interior angles of a triangle is 180°.
Butoxors [25]

Answer:

  A  Alternate interior angles of parallel lines are congruent

Step-by-step explanation:

The referenced angles (1, A), (3, C) are alternate interior angles, not corresponding or exterior. The symmetric property does not apply. The only answer choice with any applicability is the one shown above. (It is also the right choice.)

7 0
3 years ago
Read 2 more answers
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