SOLUTION: 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

Algebra ->  Radicals -> SOLUTION: 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       Log On


   

Question 993752: I'm really having a tough time with this problem, can you help me?
here is the problem:
6sqrt%2812%29-8sqrt%2850%29+9sqrt%2872%29
I rewrote it using prime factorization and got this:
6%2A2sqrt%283%29-8%2A5sqrt%282%29+9%2A3%2A2sqrt%282%29
I simplified to this:
12sqrt%283%29-40sqrt%282%29+54sqrt%282%29
I tried to solve this and got 12sqrt%283%29+14sqrt%282%29 but the answer key shows the answer as: 57sqrt%283%29-40sqrt%282%29 Can you tell me how they got that?
Found 2 solutions by Alan3354, MathTherapy:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
I'm really having a tough time with this problem, can you help me?
here is the problem:
6sqrt%2812%29-8sqrt%2850%29+9sqrt%2872%29
I rewrote it using prime factorization and got this:
6%2A2sqrt%283%29-8%2A5sqrt%282%29+9%2A3%2A2sqrt%282%29
I simplified to this:
12sqrt%283%29-40sqrt%282%29+54sqrt%282%29
I tried to solve this and got 12sqrt%283%29+14sqrt%282%29 but the answer key shows the answer as: 57sqrt%283%29-40sqrt%282%29 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.

Answer by MathTherapy(10858) About Me  (Show Source):
You can put this solution on YOUR website!
I'm really having a tough time with this problem, can you help me?
here is the problem:
6sqrt%2812%29-8sqrt%2850%29+9sqrt%2872%29
I rewrote it using prime factorization and got this:
6%2A2sqrt%283%29-8%2A5sqrt%282%29+9%2A3%2A2sqrt%282%29
I simplified to this:
12sqrt%283%29-40sqrt%282%29+54sqrt%282%29
I tried to solve this and got 12sqrt%283%29+14sqrt%282%29 but the answer key shows the answer as: 57sqrt%283%29-40sqrt%282%29 Can you tell me how they got that? 
Your answer is correct.

For the answer key to be correct, the problem would have to be: 6sqrt%2812%29-8sqrt%2850%29+highlight_green%289sqrt%2875%29%29, as opposed to: 6sqrt%2812%29-8sqrt%2850%29+highlight_green%289sqrt%2872%29%29

It may've been highlight_green%28sqrt%2875%29%29, and not highlight_green%28sqrt%2872%29%29. Check the problem!! Maybe you copied it incorrectly!