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OpenStudy (anonymous):
\[5\sqrt{24} \times 3\sqrt{10}\]
OpenStudy (anonymous):
If you are looking for the answer to (5sqrt24) x (3sqrt10) the answer is 54,000
OpenStudy (anonymous):
How did you get that?
OpenStudy (anonymous):
i got this by multiplying
jimthompson5910 (jim_thompson5910):
It might help to simplify first before you multiply. So let's simplify \(\large \sqrt{24}\) first.
\[\large \sqrt{24} = \sqrt{4*6}\]
\[\large \sqrt{24} = \sqrt{4}*\sqrt{6}\]
\[\large \sqrt{24} = 2\sqrt{6}\]
Notice how I factored 24 into 4*6 and 4 is a perfect square.
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jimthompson5910 (jim_thompson5910):
Since 10 doesn't have any factors which are perfect squares (other than 1), this means that \(\large \sqrt{10}\) cannot be simplified
jimthompson5910 (jim_thompson5910):
So that means we'll have this
\[\large 5\sqrt{24} \times 3\sqrt{10}\]
\[\large 5*2\sqrt{6} \times 3\sqrt{10}\]
\[\large 10\sqrt{6} \times 3\sqrt{10}\]
\[\large (10*3)*(\sqrt{6}*\sqrt{10})\]
\[\large 30\sqrt{6*10}\]
I'll let you finish up.
OpenStudy (anonymous):
Now if I have \[2\sqrt{6}\]
can i multiply it with \[3\sqrt{10}\]?
jimthompson5910 (jim_thompson5910):
yes you can
jimthompson5910 (jim_thompson5910):
you do so by multiplying the outer coefficients together
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jimthompson5910 (jim_thompson5910):
then combining the roots using the idea that \(\large \sqrt{x}*\sqrt{y} = \sqrt{x*y}\)
OpenStudy (anonymous):
\[6\sqrt{60}\]
jimthompson5910 (jim_thompson5910):
Don't forget about the 5 as well
OpenStudy (anonymous):
60= 2,30= 2,15 = 3,5
2 \[\sqrt{60}=2\sqrt{15}\]
OpenStudy (anonymous):
what five?
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OpenStudy (anonymous):
wait so the answer is 12 sq root 15?
jimthompson5910 (jim_thompson5910):
up at the top you have "5 sq root 24 times 3 sq root 10"
so the first number in the expression
OpenStudy (anonymous):
oh yeah
OpenStudy (anonymous):
so it's 30 sq root 60?
jimthompson5910 (jim_thompson5910):
now simplify \(\large \sqrt{60}\)
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OpenStudy (anonymous):
\[30\sqrt{60}=30(2\sqrt{15})=60\sqrt{15}\]
jimthompson5910 (jim_thompson5910):
you are correct, the final answer is \(\large 60\sqrt{15}\)
OpenStudy (anonymous):
could you help me with one more similar problem really quick?
jimthompson5910 (jim_thompson5910):
sure
jimthompson5910 (jim_thompson5910):
go for it
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OpenStudy (anonymous):
\[\sqrt{3}\times \sqrt{27}\]
jimthompson5910 (jim_thompson5910):
I would simplify \(\large \sqrt{27}\) first
jimthompson5910 (jim_thompson5910):
or I guess you could just combine the roots and multiply
jimthompson5910 (jim_thompson5910):
either way works
OpenStudy (anonymous):
so i would just make it
\[\sqrt{3}\times3\sqrt{3}\]
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jimthompson5910 (jim_thompson5910):
then you combine the roots and multiply
OpenStudy (anonymous):
which is just 3 * 3 =9
jimthompson5910 (jim_thompson5910):
then take the square root of that to get 3
OpenStudy (anonymous):
oh snap I forgot about that okay that makes sense
jimthompson5910 (jim_thompson5910):
that's ok, i have brain farts all the time too
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OpenStudy (anonymous):
could you help me with one last question? i swear thats it after this
jimthompson5910 (jim_thompson5910):
sure I'd love to
OpenStudy (anonymous):
\[\frac{ 3 + \sqrt {7}}{ 2 - \sqrt 10 }\]
OpenStudy (anonymous):
i know i have to multiply the top and bottom by 2 + sqrt 10
jimthompson5910 (jim_thompson5910):
good start, what does that give you once you do?
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to get
\[\frac{ 6 + 3\sqrt7+2\sqrt7+\sqrt70 }{ -6 }\]
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OpenStudy (anonymous):
and that's where I'm stuck
jimthompson5910 (jim_thompson5910):
what are the like terms in this case?
OpenStudy (anonymous):
6?
jimthompson5910 (jim_thompson5910):
what else
OpenStudy (anonymous):
sqrt 7?
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jimthompson5910 (jim_thompson5910):
correct, if you replace \(\large \sqrt{7}\) with z (or any other variable really), you go from
\[\large 3\sqrt7+2\sqrt7\]
to
\[\large 3z + 2z\]
and that looks much clearer in terms of spotting the like terms (and combining them)
OpenStudy (anonymous):
so would i multiply those two and get (3 * 2) (sqrt7 * sqrt7) = 6*7=42?
jimthompson5910 (jim_thompson5910):
nope, look at my last message
OpenStudy (anonymous):
wait no i wrote that wrong it's supposed to be
\[\frac{ 6+3\sqrt10+2\sqrt7+\sqrt70 }{ -6 }\]
jimthompson5910 (jim_thompson5910):
oh right, not sure where the root 10 went...
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jimthompson5910 (jim_thompson5910):
at this point, there's not much you can do
OpenStudy (anonymous):
I just wrote it down wrong. This is where I have trouble simplyfing it.
jimthompson5910 (jim_thompson5910):
because there are no like terms in the numerator
OpenStudy (anonymous):
what bout the 6 and -6?
OpenStudy (anonymous):
*about
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jimthompson5910 (jim_thompson5910):
I guess you could go from
\[\frac{ 6+3\sqrt{10}+2\sqrt{7}+\sqrt{70} }{ -6 }\]
to
\[\frac{ -6-3\sqrt{10}-2\sqrt{7}-\sqrt{70} }{ 6 }\]
jimthompson5910 (jim_thompson5910):
but that's about all you can do really
OpenStudy (anonymous):
i thought you could get rid of the 6 and 6
jimthompson5910 (jim_thompson5910):
if you do that, you would have to break up the fraction
OpenStudy (anonymous):
oh whoops
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OpenStudy (anonymous):
okay that's it haha thank you so much for all the help I really appreciate it