chris65 2 years ago slove equations and put it into a matrices 4t-5r=21 3t-7r=18

1. lilg132

4t - 5r = 21 (multiply all by 7) 3t - 7r = 18 (multiply all by -5) 28t - 35r = 147 -15t + 35r = 90 add the two equations together 13t =237 t = 18.230769230769230769230769230769 4(18.230769230769230769230769230769) - 5r = 21 72.923076923076923076923076923077 - 5r = 21 72.923076923076923076923076923077 - 21 = 5r 51.923076923076923076923076923077 = 5r 10.384615384615384615384615384615 = r not sure if this is right

2. chris65

i got the answer of t=57/13 and r=-9/13 but i have to put it into a matrices

3. lilg132

lol damn i had it right the first time

4. lilg132

let me write it out again

5. chris65

ok but i dont know how to put it into a matrix

6. lilg132

4t - 5r = 21 3t - 7r = 18 4t = 21 + 5r divide everything by 4 t = 5.25 + 1.25r 3(5.25 + 1.25r) - 7r = 18 15.75 + 3.75r - 7r = 18 15.75 - 18 = 7r - 3.75r -2.25 = 3.25r -2.25 / 3.25 = 3.25r / 3.25 -9/13 = r 4t - 5(-9/13) = 21 4t + 45/13 = 21 4t = 21 - 45/13 4t = 228/13 4t / 4 = (228/13)/4 t = 57/13

7. lilg132

ok let me work out how to put into matrix

8. chris65

ok i got all that i just dont no how to make a matrix out of that

9. lilg132

no idea with matrixes going to have to ask someone else sorry

10. lilg132

im out of here bye

11. AriPotta

|dw:1354243922660:dw|

12. chris65

|dw:1354244060647:dw|

13. chris65

thats what i have to put my answer in

14. AriPotta

only two sets of brackets?

15. chris65

yes

16. AriPotta

are they only looking for Dt and Dr?

17. chris65

yes

18. AriPotta

|dw:1354244183257:dw| there. lol

19. chris65

lol

20. chris65

ok i got another problem for ya

21. AriPotta

mer.

22. chris65

3x-z=4 x+y+7z=0 3x+y-z=4 and x=148/119 y=16/17 z=1

23. chris65

that also has to be into a matrices

24. AriPotta

oh. idk about 3 variable ones. i'm sorry :/

25. chris65

ok thanks