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I need help on this, I don't get this

I need help on this, I don't get this-example-1
User Kivan
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1 Answer

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Answer: x = 4

=============================================

Work Shown:

Isolate y in the first equation

2x+y = 5

y = 5-2x .... subtract 2x from both sides

y = -2x+5

Then plug this into the other equation

-3x - 5y = 3

-3x - 5( y ) = 3

-3x - 5( -2x+5 ) = 3 .... replace y with -2x+5

-3x + 10x - 25 = 3 .... distribute

7x-25 = 3

7x = 3+25 .... adding 25 to both sides

7x = 28

x = 28/7 .... divide both sides by 7

x = 4 is the answer

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

Optional Section:

Use this value of x to find y

y = -2x+5

y = -2(4)+5

y = -8+5

y = -3

Then we can check our answers by plugging them into the original equations

2x + y = 5

2(4) - 3 = 5

8 - 3 = 5

5 = 5

That confirms the first equation. Repeat for the second equation

-3x - 5y = 3

-3(4) - 5(-3) = 3

-12 + 15 = 3

3 = 3

We've confirmed both equations, so (x,y) = (4, -3) is the solution to this system. This system is considered independent and consistent.

Graphing the two original equations will show that they intersect at (4, -3).

User Letisia
by
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