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## Mttblink Group Title Help with these:/ I don't understand 11 months ago 11 months ago

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1. Mttblink Group Title

2. hartnn Group Title

can you find slope of any given line ?

3. hartnn Group Title

like say , x-5y = -10 is a line. can you find slope of this line first ?

4. Mttblink Group Title

Uh no not really... with a quick review I probably can

5. hartnn Group Title

good, so i have x-5y =-10 i will try to isolate y and bring it in the form y=mx+c where m=slope so, x=5y-10 5y = x+10 y= (1/5)x +2 got this ?

6. Mttblink Group Title

Yeah I got it

7. hartnn Group Title

cool, so can you find the slope of x -3y=9 line ? in same way

8. hartnn Group Title

oh and i forgot to mention, y= (1/5)x +2 comparing with y=mx+c gives, m=slope = 1/5

9. Mttblink Group Title

x-37=9 -3y=x+9 Y=(1/3)x+3

10. Mttblink Group Title

So slope would be 1/3 I assume?

11. hartnn Group Title

correct! :) now try to find slopes of other 3 lines also! and tell me, so that i will verify :)

12. Mttblink Group Title

4x+2y=5 2y=-4x+5 Y-(-1/2)x+2.5 ?

13. hartnn Group Title

2y=-4x+5 is correct, but then divide both sides by 2 what u get ?

14. Mttblink Group Title

10x-5y=8 -5y=10x+8 Y=-2x+1.6?

15. hartnn Group Title

10x-5y=8 -5y=10x+8 <<<<<<NO! -5y = -10x +8

16. Mttblink Group Title

and you would get y=-2+2.5

17. Mttblink Group Title

Ahh okay -10 so the problem would come out with a positive 2x

18. hartnn Group Title

yes, so the slope will be m= 2 , right ?

19. Mttblink Group Title

Yes

20. hartnn Group Title

4x+2y=5 slope = -2 make a note of all slopes, we'll need them

21. hartnn Group Title

and what about last line ?

22. Mttblink Group Title

4x+y=-1 Y=-4x-1

23. hartnn Group Title

so, slope =?

24. Mttblink Group Title

-4

25. hartnn Group Title

Good! now here's the rule : slope of parallel lines are equal! so, for the last one, slope of line parallel to 4x+y=-1 will also be m=-4 :) so, for last, the correct option will be C) m=-4 got this ? in same way, can you match the 2nd last and 3rd last ?

26. Mttblink Group Title

Yeah I got it, Thanks a ton man. You need to be my teacher xD

27. hartnn Group Title

haha, :) but we still require to do the 1st 2 !

28. hartnn Group Title

another rule, product of slopes of perpendicular lines = -1  so, for 1st one we had slope = 1/5 let slope of perpendicular line be m. so, $$\Large m\times (1/5)=-1$$ find m from here :)

29. Mttblink Group Title

1st one is m=1/5? 2cnd one is m=1/3? It seems like these would be the answers but they are not possible to be selected.

30. Mttblink Group Title

Ahhhh okay

31. hartnn Group Title

because perpendicular lines follow different rule :)

32. Mttblink Group Title

Well I still don't exactly get how it goes from (1/5) to -1...

33. hartnn Group Title

product of slopes = -1 is the rule so, m (1/5) =-1 multiplying by 5, m = -5 got this ?

34. hartnn Group Title

multiplying by 5 on both sides.

35. Mttblink Group Title

I'm confused on the product of slopes part, I get the multiplying on both sides. So like can you explain the product of slopes rule.. I tried looking it up on google but nothing I can comprehend really comes up.

36. hartnn Group Title

if say line 1 has slope M1 and line 2 has slope M2 now if these 2 lines are perpendicular to each other, then M1*M2 =-1

37. hartnn Group Title

another way to remember the same thing is, the slope of line is negative reciprocal of the perpendicular line, so, slope of line perpendicular to line with slope 1/5 will be - (1/(1/5)) = -5

38. hartnn Group Title

so, thats your 1st one, m =-5 for 2nd one, we had slope = 1/3, so m *(1/3) = -1 so, m=-3 is the answer to 2nd one :)

39. Mttblink Group Title

Okay, so basically whenever there is a fraction just take (1/_) blank space number lol

40. hartnn Group Title

you forgot the negative :P -1/ stuff

41. hartnn Group Title

but this only applies to perpendicular lines

42. hartnn Group Title

for parallel lines, slope are equal

43. Mttblink Group Title

Oh I see says the blind man

44. hartnn Group Title

what who ?

45. hartnn Group Title

lol

46. hartnn Group Title

i hope you got the entire problem clearly ?

47. hartnn Group Title

ask if any doubts anywhere

48. Mttblink Group Title

Yeah I get it now man thanks a ton

49. hartnn Group Title

welcome ^_^