1. Tahmina

Write the equation of a line that is: perpendicular to 9x + 3y = 15 and goes through the point (-6, 7)

2. Brittni0605

What do you know about the slopes of perpendicular lines?

3. Fox375

y = - 3x + 18

4. Fox375

i used a program called geogebra.

5. Tahmina

how did u get that

6. Fox375

Geogebra

7. Fox375
8. Brittni0605

Programs are good, but its important to know how to do it by hand.

9. Tahmina

I know i found it but I dont want to use it

10. Brittni0605

11. Fox375

It is very simple yo use. They even provide help for you too solve these kind of probelms.

12. Tahmina

Yes I need your help Brittni0605

13. Brittni0605

Ok, so what do you know about the slopes of perpendicular lines?

14. Tahmina

you have to multiply them by -1

15. Tahmina

rite? idk

16. Brittni0605

Umm, sort of on the right track. Perpendicular lines have slopes that are negative reciprocals. Do you know what that means?

17. Tahmina

No can u be a little clear on that?

18. Tahmina

So you mean B mutiply 3 *-1/3

19. Tahmina

i got 3 because its the slope isnt it?

20. Brittni0605

|dw:1355586908724:dw|

21. Tahmina

Okay whats the slope then wait you need to find the slope first rite?

22. Brittni0605

Yes.

23. Tahmina

slope is 3

24. Tahmina

rite?

25. Brittni0605

No, its not 3. Show me your work.

26. Tahmina

okay

27. Tahmina

|dw:1355587318034:dw|

28. Brittni0605

Your work is correct. But you said the slope is 3. Your work shows something different.

29. Tahmina

oh sorry its negative 3 thanks for showing that

30. Brittni0605

No prob. SO, now that you know the slope of your line is -3, what is the slope of its perpendicular line?

31. Tahmina

\[-3 *1/3\]

32. Tahmina

rite?

33. Tahmina

wait what about the points (-6,7)

34. Brittni0605

No, remember if the slope of your line is -6, the slope of its perpendicular line is the negative reciprocal (1/6)

35. Tahmina

wiat whats the slope of the perspendicular then

36. Tahmina

*perpendicular

37. Brittni0605

Perpendicular slope is the negative reciprocal of the slope of your line

38. Tahmina

so the slope of my line is -3 that means my perpendicular slope is -3 *1/3 rite?

39. Brittni0605

No, you're not multiplying anything.

40. Tahmina

so my perpendicular lines slope is 1/3 rite

41. Brittni0605

Yes.

42. Tahmina

so do i substitute with y=mx+b

43. Brittni0605

Yes.

44. Tahmina

can u check my work???/

45. Brittni0605

46. Tahmina

okay imm attach it

47. Brittni0605

Ok.

48. Tahmina

Nevermind my computers having problems?

49. Brittni0605

Umm, ok