## ganeshie8 one year ago How is this possible $\frac{1}{4}-\frac{3}{8} = \frac{1}{2}$

1. Astrophysics

It's not :o

2. CLOBBER02

help me

3. ganeshie8

just found an awesome reasoning for how that is possible from one of our users xD

4. Astrophysics

Haha, that's great :))

5. random231

rofl xD

6. random231

wow youre a patient helper ganeshie ;)

7. UnkleRhaukus

$\frac14-\frac38\\ =^? \frac{1-3}{4-8}\\ = \frac24\\ =\frac12\\$

8. ganeshie8

Haha was just thrilled by how that user came up with such cute reasoning!

9. Astrophysics

These kids on here are really smart, they just need the right push :P

10. UnkleRhaukus

|dw:1433833984854:dw|

11. Astrophysics

Sorcery!

12. ganeshie8

thats my fav one! wrong reasoning, right answer they are called happy fractions or something...

13. Astrophysics
14. Astrophysics
15. ganeshie8

interesting, im still a bit clueless about identifying the flaw in that proof(youtube link) showing all triangles are equilateral ...

16. ParthKohli

Haha, nice solution. How do you solve this though?

17. UsukiDoll

I got -1/8 on this T_T!

18. ParthKohli

Wolfram says the answer is $$-1/8$$. How did it get to that figure?

19. geekfromthefutur

Without wolfram math i wouldn't be smart about math lol

20. UsukiDoll

lcd yo!

21. ParthKohli

What...?

22. UsukiDoll

$\frac{2}{2} \times \frac{1}{4} - \frac{3}{8} \rightarrow \frac{2}{8} - \frac{3}{8} \rightarrow = -\frac{1}{8}$

23. UsukiDoll

find the least common denominator on this... the sign was missing when I saw that reasoning

24. ParthKohli

Oh wow! Interesting method. Nice.

25. UsukiDoll

actually that's common x.x anyone out there can use least common denominator

26. ParthKohli

No I can't.

27. UsukiDoll

and by the way a - sign was dropped in that image....when clobber did the arithmetic 2-3 = -1 for the numerator

28. UsukiDoll

but he drew a 1 instead of a -1

29. ParthKohli

I just believed that these problems were supposed to be solved by Wolfram because they're hard, so I always plugged these numbers into Wolfram. Didn't know people could actually solve these.

30. geekfromthefutur

Well you can it just takes a while longer to solve the problem but all that matters that getting it solved. Because not every problem is going to be easy as 2 + 2

31. UsukiDoll

32. ParthKohli

Anyway, thank you for sharing this method! More people should know about it. I'm about to finish high-school and my classmates also use Wolfram for solving fractions.

33. ganeshie8

lol honestly i never found a satisfying explanation for why common denominator is needed when adding/subing fractions

34. UsukiDoll

O__________________________O! Okay, that's fine for checking answers, but students shouldn't be dependent on it. My university doesn't allow calculators or computers. Have fun with that

35. Astrophysics

I don't think any mathematics department does ;)

36. UsukiDoll

wolfram shouldn't be abused... and sometimes even Mr.Wolfy himself makes mistakes

37. geekfromthefutur

Yea it cant solve every problem.

38. UsukiDoll

there was a professor who allowed everything ... book, calculator...tablet...but he retired recently

39. ParthKohli

Haha, ganeshie, it should make sense though. You can add 1/8th and 4/8th of a cake like that, but you can't add 1/8th and half of a cake.

40. ParthKohli

I will have to revise my fractions after finishing calculus.

41. UsukiDoll

oh lol @UnkleRhaukus you just broke a math rule with your example.

42. Astrophysics

Oh I thought you were joking the whole time parth

43. ParthKohli

;)

44. UnkleRhaukus

all triangles are equilateral

45. ParthKohli

You hoped I was joking the whole time. :P

46. ParthKohli

I guess I stretched it way too far.

47. ganeshie8

nope it is fine, the joke is obvious to everyone ;p

48. Miracrown

I knew it

49. Astrophysics
50. Miracrown

LOL

51. ganeshie8

should msg it to one of his gfs lol

52. UsukiDoll

omg dan.

53. Miracrown

ikr @ganeshie8 ;)

54. Astrophysics

Anyways check out those false proofs from that link, pretty cool :)

55. ParthKohli

From comments: The mistake lies in the drawing. The lines are too sloppy and if you actually draw it out, you will see C* always lies on the other side of C (or B* on the other side of B), so subtracting C*C from AC does not make the conclusion valid anymore.

56. ParthKohli

 one of his gfs lol  Subtle, I like it.

57. UsukiDoll

last semester I accidentally typed "Dan I love you" instead of "Dan I need your help" because I was working on a matlab code. T_T! I had to type to two people on os that it wasn't spam and it was an accident.

58. Astrophysics
59. ParthKohli

Don't worry, Dan's a player. He just gets everyone to fall in love with him.

60. UsukiDoll

This was before I had glasses, so yeah...I couldn't see well with small text

61. geekfromthefutur

Lol. and i wonder who else hes with xD

62. ParthKohli

@Astrophysics Holy crap, hahaha.

63. Miracrown

I like it how this post has completely gone off topic

64. Astrophysics

Sorry haha

65. ParthKohli

To be fair, the topic isn't something eye-catching.

66. Miracrown

All good @Astrophysics :)

67. Miracrown

@ganeshie8 can you please give us another prob?

68. Astrophysics

What is $\huge 2^{2014}-2^{2013}?$

69. geekfromthefutur

ok

70. ParthKohli

$2^{2013}$

71. geekfromthefutur

crap it repeated my statment

72. ParthKohli

Sorry, wrong answer. Should be$\huge 2^{2013}$

73. ParthKohli

Or maybe you could do it "that" way:$\large 2^{2014} - 2^{2013} = 2^{2014 - 2013} = 2^1 = 2$

74. Astrophysics

Yeah haha, $\huge 2^{2013}(2) - 2^{2013} \implies 2^{2013}(2-1) = 2^{2013}$

75. Miracrown

Next one

76. Astrophysics

Geniuses...ok what number am I thinking of?

77. ParthKohli

78. Miracrown

96

79. Astrophysics
80. ParthKohli

You're just cashing in on hartnn's efforts.

81. ParthKohli

In hartnn's pic, his arms are all bulgy and muscular. Coincidence? I think not.

82. zzr0ck3r

83. geerky42

$$\color{blue}{\text{Originally Posted by}}$$ ganeshie8 How is this possible $\frac{1}{4}-\frac{3}{8} = \frac{1}{2}$ $$\color{blue}{\text{End of Quote}}$$ It's isn't? What's so amazing about it anyway? All I see is user just happen to think that subtraction works like multiplication, hence did$$\frac{1}{4}-\frac{3}{8} = \frac{1-3}{4-8}$$

84. UsukiDoll

^ which broke a math rule...