## ayee_ciera one year ago CAN ANYONE HELP ME PLS I WILL FAN AND MEDAL TO ANYONE THT HELPS!

1. ayee_ciera

What is the solution to the following system? 3x+=3y=10 -9x-9y=-30

2. FireKat97

try posting up your working so far

3. ayee_ciera

I haven't got anything im stuck

4. FireKat97

okay so when you have questions like these, there are two methods you can go to; substitution method and elimination method do you know how these work?

5. ayee_ciera

yes ofc

6. FireKat97

okay so pick whichever one you want to use for this particular question..

7. ayee_ciera

um.. substitution?

8. anonymous

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9. anonymous

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10. anonymous

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11. anonymous

de ansa us d

12. anonymous

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13. anonymous

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14. anonymous

( ͡o ͜ʖ ͡o)

15. FireKat97

okay so if you want to substitute, write either one of the two equations in the form of y = ... or x = ....

16. ayee_ciera

but how?

17. FireKat97

okay so say we pick the first equation and want to write it in terms of x... so 3x + 3y = 10 we want to isolate x, do you have any ideas how we may do so?

18. ayee_ciera

plug in -9x...?

19. FireKat97

um no, we want x by itself, so we can start off by subtracting 3y from both sides of the equation, to get 3x + 3y - 3y = 10 - 3y and now we simplify..

20. FireKat97

so we get 3x = 10 - 3y

21. ayee_ciera

can it also be 3x=3y+10?

22. ayee_ciera

@FireKat97

23. FireKat97

no because we subtracted 3y from the right hand side, we didn't add it

24. FireKat97

because only through subtracting 3y from both sides, could we cancel 3y on the left hand side and try to isolate the x

25. ayee_ciera

so we divide 10-3y by 3x? @FireKat97

26. FireKat97

close.. we divide it by 3 alone :)

27. FireKat97

that way we get x = (10 - 3y)/3

28. ayee_ciera

$x=\frac{ 10-3y }{ 3 }$

29. ayee_ciera

@FireKat97

30. FireKat97

yup thats correct! Now we want to substitute this into our second equation and simplify..

31. ayee_ciera

$-9(\frac{ 10-3y }{ 3 })-9y=-30$ so tht? @FireKat97

32. FireKat97

Yup! thats right! now we have to simplify

33. ayee_ciera

$-9(\frac{10-3y }{ 3 })-9y=-30$ $-21y-9y=-30$ $+9y+9$ -30=-30 @FireKat97

34. FireKat97

umm let start off by opening and simplifying the brackets first, so just simplify -9(10 - 3y( and tell me what you get

35. FireKat97

)*

36. ayee_ciera

-21 @FireKat97