Question 993752
I'm really having a tough time with this problem, can you help me?
here is the problem:
{{{6sqrt(12)}}}-{{{8sqrt(50)}}}+{{{9sqrt(72)}}}

I rewrote it using prime factorization and got this:
{{{6*2sqrt(3)}}}-{{{8*5sqrt(2)}}}+{{{9*3*2sqrt(2)}}}

I simplified to this:
{{{12sqrt(3)}}}-{{{40sqrt(2)}}}+{{{54sqrt(2)}}}

I tried to solve this and got {{{12sqrt(3)}}}+{{{14sqrt(2)}}} but the answer key shows the answer as: {{{57sqrt(3)}}}-{{{40sqrt(2)}}} Can you tell me how they got that? 
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The answer key is wrong.  It doens't happen often, but it does.
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Your answer is correct.