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A seemingly easy question that's very hard

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by parallel_chase » Wed Aug 06, 2008 4:36 pm
lets solve this separately
49+49 =98

49+49^2 = 49 (1+49) = 49*50

98/(49*50) = 2/50 =1/25

Hope this helps.
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by vishubn » Wed Aug 06, 2008 4:37 pm
(49 + 49)/ (49+49^2)
-->49(1+1)/49(1+49)

now we end up with 2/50 => 1/25

the whole idea is to factorize

vishu
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by Stockmoose16 » Wed Aug 06, 2008 4:39 pm
vishubn wrote:(49 + 49)/ (49+49^2)
-->49(1+1)/49(1+49)

now we end up with 2/50 => 1/25

the whole idea is to factorize

vishu
Why wouldn't it be:

49+49 / 49 + (49*49)

Since 49^2 = 49*49, you'd have to multiply that out first (by PEMDAS)... why is this wrong?
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by Stockmoose16 » Wed Aug 06, 2008 4:48 pm
vishubn wrote:(49 + 49)/ (49+49^2)
-->49(1+1)/49(1+49)

now we end up with 2/50 => 1/25

the whole idea is to factorize

vishu
In the denominator, why would you factorize (49+49^2) into 49 (1+49)? Wouldn't it be 49 (1+1^2)

That would mean the equation would be:

49 (1+1) /49 (1+1^2)

that would then be: 49 *2 / 49 *2 = 1

Why is this wrong? Ugh, this is so frustrating.
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by parallel_chase » Wed Aug 06, 2008 4:56 pm
Dude, keep it cool. Dont worry you'll get it.
In the denominator, why would you factorize (49+49^2) into 49 (1+49)? Wouldn't it be 49 (1+1^2)
first of all what is (49+49^2) = 49 + 49*49

Now you take 49 common 49 (1+49) = 49*50

Let me know if you still have any doubts.
Last edited by parallel_chase on Wed Aug 06, 2008 4:56 pm, edited 1 time in total.
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by vishubn » Wed Aug 06, 2008 4:56 pm
why wouldi do that 49(1+1^2) is again 49 ( 1+1) .. when we multiply it back we get (49+49) and not (49+49^2)
coz eg (3+3^2) is equal to 3 (1+3)=12 and not 3 (1+1^2)= 3(2) =6


i hope it helps

Vishu
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by Stuart@KaplanGMAT » Wed Aug 06, 2008 8:05 pm
Stockmoose16 wrote:
Why wouldn't it be:

49+49 / 49 + (49*49)

Since 49^2 = 49*49, you'd have to multiply that out first (by PEMDAS)... why is this wrong?
That's fine... but you still do the same thing next:

2*49/(1*49 + 49*49)

Then factoring out a 49 in the denominator:

2*49/(1+49)*49

2*49/50*49

We can "cancel out" a 49 on the top and bottom to get:

2/50 = 1/25

Here's another way you can think of it... what if the original had been:

(x + x)/(x + x^2)

we'd then have:

2x/x(1+x)

or

2/(1+x)

Now sub in x=49 and you'll see that the exact same mathelogic applies!
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