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Help me Please

solve for x and y

 

x+3y= -3

4x+3y= 6

 Oct 18, 2017
 #1
avatar+9916 
+1

  x + 3y = - 3     |*(-1)

4x + 3y =   6

 

 - x - 3y =  3    

4x + 3y =   6

3x        =   9     | : 3

  x        =   3 

 

3 + 3y = - 3   | - 3

      3y = - 6   | : 3

        y =   2

 

laugh

 Oct 18, 2017
 #3
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0

It seems like you made an error solving for y. The correct answer should be y= -2.

 

All the best!

Guest Oct 18, 2017
edited by Guest  Oct 18, 2017
 #2
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+1

Okay, so we begin by picking one of the equations, and solving for either x or y.

 

I will pick equation 1, and solve for x:

 

\(x=-3-3y.\)

 

We now insert this modifyed version of equation 1 into equation 2. By that i mean that we replace x in equation 2 with -3-3y. We do this and obtain:

 

\(4\cdot(-3-3y)+3y=6\)

 

which gives us that

 

\(y=-2.\)

 

What remains now is to replace y with -2 in any of our expressions that contain both x and y. Its the easiest to insert it into x=-3-3y, since we would otherwise have to solve for x again! We do this and obtain;

 

\(x=-3-3\cdot(-2)=3.\)

.
 Oct 18, 2017

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