+0

0
68
3
+120

solve for x and y

x+3y= -3

4x+3y= 6

ManuelBautista2019  Oct 18, 2017
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#1
+8826
+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

Omi67  Oct 18, 2017
#3
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
+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;

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

Guest Oct 18, 2017

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