## MaeganR 2 years ago Write an equation in point-slope form of the line through the given points. Then write the equation in slope-intercept form. #11. (4,0), (-2,1) #12. (-3,-2), (5,3) #13. (-5,1), (3,4) Thats all they give you. And YES I do know the Formulas: Point-slope: y-y1=m(x-x1) Slope-intercept: y=mx+b Slope: m=y2-y1/x2-x1

1. chihiroasleaf

first.., find the slope using the third formula that you write.., then use point-slope formula to find the equation..

2. Butterfly16

m=y2-y1/x2-x1 (4, 0) (-2, 1) m=1-0/-2-4 m=1/-6 m=y2-y1/x2-x1 (-3, -2), (5, 3) m=3-(-2)/5-(-3) m=5/8 m=y2-y1/x2-x1 (-5, 1) (3, 4) m=4-1/3-(-5) m=3/8

3. MaeganR

SLOPE= -0.16

4. MaeganR

@Butterfly16 Thats what I've done before, but then people come along, and tell me I'm wrong! ):

5. MaeganR

And why are you finding the slope 3 times?

6. chihiroasleaf

because you have three questions and each question have equation... :)

7. MaeganR

oh, well I'm on #11.

8. Butterfly16

y-y1=m(x-x1) (4,0), (-2,1) y-0=(1/-6)(x-4) y-0= -0.16x+0.7 y=-0.16x+0.7 Yeah, I just finding the slope for all of them. :o)

9. MaeganR

Im so freaking confused.

10. chihiroasleaf

now.., using the similar way.., you can solve questions #12 and #13 can you? :)

11. Butterfly16

y1 and x1 just stand for the points. So (4, 0) is the point, so y1 is 0 and x1 is 4. That would the equation for the point-slope form for that set of points.

12. MaeganR

but you have to write it in point-slope form?!

13. Butterfly16

Then, I guess you can just plug in the numbers into the point-slope form so it'd just be: y-0=(1/-6)(x-4)

14. MaeganR

but don't you have to do 2 equations because of (4,0) and (-2,1)

15. chihiroasleaf

@Butterfly16 has write it in slope-intercept form slope-intercept form is y = mx+ c , No.., points (4,0) and (-2,1) are on the same line.., so just choose one of them..

16. MaeganR

|dw:1358115682620:dw|

17. MaeganR

because like that?

18. Butterfly16

Yip, the line would look like that. :o)

19. MaeganR

|dw:1358115910689:dw|

20. chihiroasleaf

yup.., it's for the second line... :)

21. Butterfly16

Awesome job! :o)

22. MaeganR

y-y1=m(x-x1) y--2=1/2(x--3) help

23. Butterfly16

The points for number 12?

24. MaeganR

@erdog82 Kinda.

25. MaeganR

#12. i got that far but I'm stuck now.

26. Butterfly16

y-y1=m(x-x1) (-3, -2) (5, 3) y-(-2)=(5/8)(x-(-3)) y+2=0.625x-1.875 y=0.625x-3.875

27. MaeganR

but y=mx+b

28. Butterfly16

Yup, so for #12 it'd be y=0.625x-3.875

29. MaeganR

but thats y=mx-b it should be y=mx+b though right?

30. erdog82

why are you guys using decimals? fractions are easier

31. erdog82

no, it depends, if you are adding a negative, its the same as subtracting, and its okay @MaeganR

32. MaeganR

Can someone show mw how you get #13 now?

33. erdog82

ok

34. erdog82

4-1/ 3--5 (or 3+5) so what is that?

35. MaeganR

|dw:1358116987370:dw|

36. MaeganR

And @erdog82 what are you doing?

37. erdog82

how do you get from y-1= 3/8 x--5 to y=mx +b form?

38. erdog82

its as simple as adding 1 number

39. MaeganR

idk. I was trying to do it like @Butterfly16 was doing it.

40. erdog82

oh and its y-1=3/8 x+5

41. erdog82

so you add 1 to 5 and you get..

42. MaeganR

6

43. MaeganR

y=3/8x+6 ?

44. erdog82

so its y=3/8 x +6

45. erdog82

yes!

46. erdog82

wasn't that easier than you thought?

47. MaeganR

A lil bit

48. erdog82

Well, it seemed like the other people were kinda confusing..

49. MaeganR

just a little

50. erdog82