1. GabriellaGurl101

When solving systems of equations, how do you determine what method to use? For the next can you please help me solve it and what all you did please

2. GabriellaGurl101

here is the problem 6x - 4y = 54 -9x + 2y = -69

3. slaaibak

You generally look at what method will be the easiest/fastest to do.

4. slaaibak

With that equation, you can see that the y coefficients are two and 4. So, it looks like a minor effort to just multiply the one equation by two, and adding them together to eliminate the y-variable

5. precal

I would do elimination but Cramer's rule is one of the fastest way to solve the system

6. GabriellaGurl101

7. GabriellaGurl101

Can you also tell what you did like step by step please and thank you :)

8. slaaibak

Sure. First multiply the second equation by 2: x2: -9x + 2y = -69 ---> -18x + 4y = -138 List the two equations and add: 6x -4y = 54 -18x + 4y = -138 __________________ -12x + 0y = -84 -12x = -84 x = 7 Now sub x back into any of the equations: 6(7) - 4y = 54 42 - 4y = 54 4y = - 12 y = -3 so x=7 and y = -3

9. GabriellaGurl101

you know how like on the second thing that you did well what goes in the middle of 6x - 4y

10. GabriellaGurl101

I can just use this and this is correct right??

11. slaaibak

nothing, I just spaced it so it is kinda in the same line of sight

12. slaaibak

yes, you can. It's correct.

13. GabriellaGurl101

thank you soo much

14. GabriellaGurl101

wait what proccess is this??

15. GabriellaGurl101

substittution??? haha i spelled it wrong lol

16. slaaibak

Nope this is elimination. My pleasure

17. GabriellaGurl101

Okay thank you