Data Sufficiency: Symbol

[ellen.chung]

I can't figure this one out... I keep getting D but the correct answer is A. (I looked for this answer in the 17 pages of the forum but couldn't find it, sorry if it's already been posted). The problem is:

The symbol (triangle, I'll use ^ for it) represents one of the four arithmetic operations: addition, subtraction, multiplication, and division. Is (5^6)^2 = 5^(6^2)?

(1) 5^6 = 6^5
(2) 2^0 = 2

The reason I got D is because:

(1) means that ^ can either be + or x. Both operations make the original equation in the question true, so this is sufficient.

(2) means that ^ can either b + or -. Both operations make the original equation in the question true as well, so this is sufficient.

I got D. But the correct answer is A... help? Thanks in advance!

[nitin_prakash_khanna]

I think you are missing something really small.

(5+6)+2 = 13 ; 5+(6+2) = 13 so its fine.

But
(5-6)-1 = -2 ; whereas 5-(6-2) = 1-4 = -3

so st 2 is not suffcient Hope you are not forgetting the PEMDAS rule, must solve the paranthesis first.

[ellen.chung]

Ohhhhh you're sooo right! Thank you for clearing that up!! Such a silly mistake, definitely good to rejog my memory. Thanks for putting it so nicely too. :)

[snipertrader]

Small correction..

It should be (5-6)-2 = -3
whereas 5-(6-2) = 1

Cheers!

I think you are missing something really small.

(5+6)+2 = 13 ; 5+(6+2) = 13 so its fine.

But
(5-6)-1 = -2 ; whereas 5-(6-2) = 1-4 = -3

so st 2 is not suffcient Hope you are not forgetting the PEMDAS rule, must solve the paranthesis first.

[RonPurewal]

Ohhhhh you're sooo right! Thank you for clearing that up!! Such a silly mistake, definitely good to rejog my memory. Thanks for putting it so nicely too. :)

at the risk of sounding like a second grade teacher, here's the best way to avoid having this sort of problem again:
if the work on a problem is easy - such as doing arithmetic - then you should DO THE WORK.

even if you didn't remember that the associative rule doesn't apply to subtraction, you could just have executed the operations (5 - 6) - 2 and 5 - (6 - 2), and found that they were different.
don't let a problem slip out of your hands by lacking the diligence to subtract - especially after you've ALREADY done all the heavy lifting in the problem!