ilovenyc 3 years ago Which of the following inequalities matches the graph? (see attached photo) A y _>_3x - 5 B y < 3x - 5 C y < 1/3x - 5 D The correct inequality is not listed.

1. ilovenyc

2. srossd

Alright, so lets pick up where we left off. Can you find two points on the line?

3. ilovenyc

(4,7)

4. srossd

Yup, that's one, good job.

5. srossd

@ilovenyc Can you find another one?

6. ilovenyc

(2,8)

7. srossd

@ilovenyc Well, go over to 2 on the x axis, and then go up until you hit the line. What y are you at? That's how you get a point.

8. ilovenyc

(2,0)?

9. srossd

@ilovenyc Not quite, although the drawing isn't too great. (2,1) is on the line.

10. srossd

Do you see how that works?

11. ilovenyc

YES

12. srossd

Great! So now, do you remember how to find the slope?

13. ilovenyc

To find the slope m of the line segment joining the points, use the slope formula

14. srossd

Right, so try doing that with (2,1) and (4,7)

15. srossd

@ilovenyc Making any progress, or do you need some help?

16. ilovenyc

need some help do i add those both together?

17. srossd

Not quite, it's more of a subtraction. Here's the slope formula: $\frac{y_2-y_1}{x_2-x_1} \; \; \; x_1 = 2 \; \; \; x_2 = 4 \; \; \; y_1=1 \; \; \; y_2=7$

18. srossd

@ilovenyc So see if you can use that to find the slope. I'll be back in just a little bit.

19. ilovenyc

@srossd so i need to subtract that

20. srossd

@ilovenyc Just use that formula I wrote, plug in the numbers. And now I'll be back in a little bit :).

21. ilovenyc

22. srossd

No, here's another hint: $\frac{7-1}{4-2}$

23. srossd

And ok, now I'm actually leaving for a little bit.

24. srossd

Just a few minutes, though.

25. srossd

@ilovenyc Alright, I'm back now. So did you get the slope from that?

26. ilovenyc

6,and 2

27. srossd

Well, 6 divided by 2.

28. srossd

So the slope ends up being 3.

29. srossd

@ilovenyc So now you know that the line will be y=3x+b. So plug in x = 0 to that, and you'll be y=b. So look at the graph, and go to the point where x=0. Find what y is.

30. srossd

|dw:1356749491751:dw|

31. ilovenyc

-4?

32. srossd

The drawing is bad again, it's actually -5. But close enough that I'm pretty sure you get it.

33. srossd

So if your equation was y=3x+b, and b=-5, what's your final equation?

34. ilovenyc

2 = 3*(-4) + b?

35. srossd

No, no - just plug in the value of b (-5) to y=3x+b. The x and y should stay.

36. ilovenyc

okay

37. srossd

@ilovenyc Do you understand, or do you need some help?

38. ilovenyc

need some help

39. srossd

Ok, so you solved for b, so just put it where b was. The equation comes out to be y=3x-5.

40. srossd

Do you see how that works, plugging in -5 for b?

41. ilovenyc

42. srossd

Actually, it's A, since everything above the line is shaded. B would be the opposite shading.

43. ilovenyc

oh okay

44. srossd

But still, good job!

45. srossd

And again, sorry for elongating this so much - I just wanted to make sure you understand how to do it.

46. srossd

@ilovenyc So do you feel like you have a good grasp on how to do this type of problem now?

47. ilovenyc

@srossd i think so...

48. srossd

Alright, good. I can make up another one for you to try if you want.

49. ilovenyc

well i have more problems that i need to do on my homework

50. srossd

Oh, ok. Need help with those?

51. ilovenyc

yes

52. srossd

Ok, want to post a new problem?

53. srossd

@ilovenyc I'll be on the lookout for a new post.