## mskyeg 2 years ago What is the solution of the system of equations?

1. mskyeg

2. hartnn

what have u tried ? tried elimination method ?

3. hartnn

subtract eq. 1 from eq. 3, what u get ?

4. mskyeg

z=-3

5. hartnn

that is correct! need further help? because its just now 2 variables to solve and u will have 3 equations for it...

6. mskyeg

oncause this is where i got stuck when i did it previously

7. mskyeg

one sec

8. mskyeg

x=-9/5 - y

9. hartnn

that u got from 2nd equation, right ? what is 3-4z= ? not -9, i suppose...

10. mskyeg

ya i got it from the second equation but i just got -5y+5y=24 after plugging it in that would mean that 0=24 which makes no sense

11. hartnn

can u show your working, so that i may point out the error. and di u understand how x=-9/5 - y is incorrect, it should be x=5-y

12. hartnn

*did

13. mskyeg

5x+5y+4z=3 5x+5y+4(-3)=3 5x+5y-12=3 5x+5y=-9 5x=-9-5y shouldn't that then equal x=-9/5-y because Im dividing both parts by 5???

14. mskyeg

oooooh oops i just realized my error

15. hartnn

so did u get x=5-y ?

16. mskyeg

5x+5y+4z=3 5x+5y+4(-3)=3 5x+5y-12=3 5x+5y=15 5x=15-5y x=3-y

17. hartnn

oops. u are correct

18. robtobey

@mskyeg Would posting the final solutions be satisfactory?

19. hartnn

now plug hat in 1st equaion

20. hartnn

*that

21. hartnn

3(3-y)+2y+(-3)=7 and u get y

22. mskyeg

y=-1???

23. hartnn

yes :)

24. mskyeg

thanks so much:)

25. hartnn

welcome ^_^

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