Solving system of equations: 3x - 2y = 6, 6x - 4y = 12

[knishroundr]

Hi I am having a big problem I have some homework but i am on vacation. I dont have my calss book to help me with. So i am hoping Someone knows how I can work this problem like the way to do it. I am not looking for an answer just how to come up with the answer.

Solve the following system of equations
3x – 2y = 6
6x - 4y = 12

 

[galactus]

Multiply the top equation by -2 and add the equations.

But a simple observation should tell you something. Note, one equation is 2 times the other.

 

[knishroundr]

Please Help

Yeh i noticed they were double each other but I am still unclear of how you do the math of combining the 2 problems. I haven't done this in 14 years and trying to take a refresher and this is not refreshing lol.

 

[galactus]

One is a multiple of the other. Infinite solutions.

If you multiply the top equation by -2 you get:




-6x+4y-12

Add that to the second equation and what do you get?.

 

[knishroundr]

Please Help

dont know if it was right but i get x-y=0

 

[jonboy]

Re: Please Help

dont know if it was right but i get x-y=0

Not quite.

\(\displaystyle \L(\,-\,6x\,+\,4y\,-2)\,+\,(6x\,-\,4y\,+2)\)

Add each individual like term (\(\displaystyle \L \,-6x\,+6x\,,\.+4y\,-4y\,\)) etc.