Can you please tell me what I am doing wrong to solve this system by Elimination?

Question

{5x-2y=4
{3x+y=9

{5x-2y=4
{-2(3x+y=9)

{5x-2y=4
{-6x-2y=-18
+________
-x = -14
Wel... by then I realize its wrong.... The answer is supposed to be (2,3) but i dont see what I can be doing wrong, Plz show me I dont wanna get stuck and desperate like the last two nights....

Answer 1

Subtract the second equation from the first, don't add them. You do this because you want the y terms to cancel out.

So you have this:
{5x-2y=4
{-6x-2y=-18

Now subtract the 2nd equation from the first:
(5x - (-6x)) + (-2y - (-2y)) = 4 - (-18)
11x + 0 = 22
11x = 22

Divide both sides by 11:
x = 2

Now plug 2 back in:
5(2) - 2y = 4
10 - 2y = 4
-2y = -6
y = 3

And plug (2,3) into the other equation to check your answer:
3(2) + (3)
= 6 + 3
= 9
So the answer checks.

Answer 2

When you multiplied the second equation by -2, and then subtracted it from the top equation to eliminate it, you forgot to change the sign on the -6x and add it to the 5x which would have given you 11x=22, x=2.

5x-2y=4
3x+y=9

5x-2y=4
-2(3x+y=9)

5x-2y=4
-6x-2y=-18

5x-2y=4
-(-6x-2y=-18) when subtracting them, don't forget to change each sign

5x-2y=4
6x+2y=18 now add them together

11x=22
x=2 sub x=2 back into either equation and solve for y

5(2)-2y=4
10-2y=4

2y=6

y=3

Answer 3

{5x - 2y = 4
{-6x - 2y = -18
(-)________ ---> This is what you did wrong, not (+) but (-), since you want to eliminate the y
11x = 22
x = 2

{3x + y = 9
3*2 + y = 9
y = 3

Answer 4

To eliminate a variable, you have to add opposites. You did -2 + -2, which only gives you -4. You need 0, so you need -2 + 2. Multiply the second original equation by 2 then do it. 11x=22, x=2, and do the rest!

Answer 5

2-y-2y=-4y

You are canceling them when you should be adding them. If you want to substract them then the rest of the equation changes.

5x-(-6x)=11x

4-(-18)=22

11x=22==>>x=2

Answer 6

Don't multiply by -2, multiply by 2 and add the 2 equations together. then you get 11x =22 or x = 2

Answer 7

to eliminate the y's since they are opposing signs just multiply 2nd equation by 2 then add.
to get 11x =22 x=2

Answer 8

you mistake is that you are subtracting if you want to eliminate -2y
so 5x-(-6x)=11x
4-(-18)=22
so x=2
The easier way would be to multiply the second equation by 2 instead of -2, then you can just add.

Answer 9

5x - 2y = 4
6x + 2y = 18----ADD

11x = 22
x = 2

6 + y = 9
y = 3

Answer 10

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