## jagr2713 one year ago 3x+6y=12 -9x+y=21

1. jagr2713

@Nnesha

2. anonymous

you have to make the variable match in both equations. The easiest way to do that would be multiply the first equation by 3

3. pooja195

What do you need to do?

4. jagr2713

don't we change the first equation into y-mx+b

5. pooja195

−9x+y+9x=21+9x(Add 9x to both sides) y=9x+21

6. Nnesha

it depends on the statement substitution , elimination/addition , or graphing ?

7. pooja195

^thats what i meant to ask.

8. jagr2713

substitution

9. pooja195

aight so continue with this −9x+y+9x=21+9x(Add 9x to both sides) y=9x+21

10. pooja195

Now that you know what y equals plug it into equation 1 3x+6(9x+21)=12 solve for x

11. jagr2713

oh I did it the other way lol

12. Nnesha

$$\color{blue}{\text{Originally Posted by}}$$ @jagr2713 don't we change the first equation into y-mx+b $$\color{blue}{\text{End of Quote}}$$ not necessarily, you don't have to write in slope intercept you can solve for x too.

13. pooja195

ok well what did u get for x?

14. jagr2713

um -2 so now we plug it into y=9(-2)+21 y=3

15. pooja195

Correct