1. carlenstar281

what are the coordinates of the x- intercept of the line 3x4y=12

2. carlenstar281

I know what the answer is (4,0) but why?

3. hartnn

to get x-intercept, put y=0 in line 3x+4y=12

4. jim_thompson5910

like hartnn is saying 3x+4y=12 3x+4(0)=12 ... plug in y = 0 3x + 0 = 12 3x = 12 x = 12/3 x = 4 So the x-intercept is the point (4,0)

5. jim_thompson5910

to find the y-intercept, just plug in x = 0 and solve for y

6. carlenstar281

Thank you Thank you for your help :)

7. jim_thompson5910

yw

8. carlenstar281

do you mind giving me a practice problem? So I can figure it out myself i really appreciate it

9. jim_thompson5910

find the y-intercept of 5x + 10y = 30

10. carlenstar281

just make up one please :)

11. hartnn

to get y-intercept, put x=0 in 5x+10y=30

12. carlenstar281

since my test is multiple choice can you give me answers to choose from?

13. hartnn

not required, but sure, 1) (0,-3) 2) (0,3) 3) (3,0) 4) (0,6)

14. hartnn

having problems ?

15. carlenstar281

yes i got x=10?

16. carlenstar281

I suck at math

17. hartnn

how you can get x=10 when i told you to put x=0 to find y-intercept :O

18. carlenstar281

i have no idea why

19. carlenstar281

one sec

20. hartnn

|dw:1362727211824:dw|

21. hartnn

can you find y from 5(0)+10y=30 ?

22. carlenstar281

sorry i got it though it would be (3,0) yes

23. hartnn

you got y=3 then, right ?? and intercepts are of the form (x,y) y co-ordinate comes after comma so, would you like to revise your answer ?

24. carlenstar281

yes its (0,3)

25. hartnn

now its correct :)

26. hartnn

want more examples?

27. carlenstar281

yes please and thank thank you for helping me :)

28. carlenstar281

I actually understand it now!!

29. hartnn

oh, you are welcome :) find x intercept of the line 2x+3y = 7 this involves fraction....

30. hartnn

try first without choices

31. carlenstar281

okay ill try it :)

32. carlenstar281

okay i know this is wrong but is it (0, 2 1/3)

33. jim_thompson5910

to find the x-intercept, you plug in y = 0 not x = 0

34. hartnn

to get x-intercept, you need to put y=0, right ?

35. carlenstar281

oh wow okay one sec sorry its late

36. hartnn

no problem, take your time :)

37. carlenstar281

alright is it (0, 3 1/2) btw thanks for your patience math is just really not my subject :/

38. jim_thompson5910

2x+3y = 7 2x+3(0) = 7 ... plug in y = 0 (not x = 0) 2x + 0 = 7 2x = 7 x = ???

39. hartnn

x=3 1/2 is correct, but same note again, intercepts are of the form (x,y) x co-ordinate comes before comma so, would you like to revise your answer ?

40. carlenstar281

No way i got it right and yes :) (3 1/2,0)

41. hartnn

yes, now (3 1/2,0) is correct :)

42. carlenstar281

Thanks again for all your help Im going to go to sleep so i can get up tomorrow again i cant thank you enough you really helped me understand this I know I will ace that test now Thank you!! :)

43. hartnn

i am glad to hear that :) and you are most welcome ^_^