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jimthompson5910 (jim_thompson5910):
What is the square root of 4 equal to?
OpenStudy (anguyennn):
2
jimthompson5910 (jim_thompson5910):
correct
What is the square root of 9 equal to?
OpenStudy (anguyennn):
3
OpenStudy (anguyennn):
and you multiply 2x2 and minus 3? correct?
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jimthompson5910 (jim_thompson5910):
so you really have `2*2-3`
evaluate that to get ??
jimthompson5910 (jim_thompson5910):
correct
OpenStudy (anguyennn):
oh ok!! thank you but what about when its √2?
jimthompson5910 (jim_thompson5910):
taking the square root of 2 doesn't give a whole number like the square root of 4 does
OpenStudy (anguyennn):
like 3√2-5√2-2√2
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jimthompson5910 (jim_thompson5910):
I don't see a square root of 2 in your problem though
jimthompson5910 (jim_thompson5910):
Oh I see now
jimthompson5910 (jim_thompson5910):
replace every copy of "square root of 2" with x
so you'll have 3x-5x-2x
simplify that to get ???
OpenStudy (anguyennn):
-4x
OpenStudy (anguyennn):
but how come you replaced it with an x?
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jimthompson5910 (jim_thompson5910):
well you don't need to, but you can think of it like that
basically you're combining like terms. In this case, all 3 terms are like terms because they have a root 2 in them
OpenStudy (anguyennn):
yes
jimthompson5910 (jim_thompson5910):
3x-5x-2x = -4x
so you now replace the x with square root of 2
so the final answer is \(\Large -4\sqrt{2}\)
OpenStudy (anguyennn):
i am still confused because for other questions it would have different numbers and i don't know how to do them
jimthompson5910 (jim_thompson5910):
like what for example?
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OpenStudy (anguyennn):
√18+√50-√8
jimthompson5910 (jim_thompson5910):
have you tried to simplify each root?
OpenStudy (anguyennn):
dividing them all by 2?
jimthompson5910 (jim_thompson5910):
think of all of the factors of 18
which factors are perfect squares?
OpenStudy (anguyennn):
I am not sure
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OpenStudy (anguyennn):
sorry
jimthompson5910 (jim_thompson5910):
factors of 18
1,2,3,6,9,18
OpenStudy (anguyennn):
ok
jimthompson5910 (jim_thompson5910):
which factor is a perfect square?
OpenStudy (anguyennn):
9
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jimthompson5910 (jim_thompson5910):
so we can say this
\[\Large \sqrt{18} = \sqrt{9*2}\]
\[\Large \sqrt{18} = \sqrt{9}*\sqrt{2}\]
\[\Large \sqrt{18} = 3*\sqrt{2}\]
jimthompson5910 (jim_thompson5910):
I factored 18 into 9*2
then I used the rule \[\Large \sqrt{x*y} = \sqrt{x}*\sqrt{y}\]
OpenStudy (anguyennn):
yes
jimthompson5910 (jim_thompson5910):
now let's do 50
what are the factors of 50?
OpenStudy (anguyennn):
1, 2, 5, 10, 25
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OpenStudy (anguyennn):
and it would be 25 that is the perfect square
jimthompson5910 (jim_thompson5910):
yes so 50 = 25*2
jimthompson5910 (jim_thompson5910):
what would \(\Large \sqrt{50}\) simplify to?
OpenStudy (anguyennn):
√25x2
jimthompson5910 (jim_thompson5910):
then break it up using the rule I posted
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OpenStudy (anguyennn):
√50= √25x2
=√25x √2
5√2
jimthompson5910 (jim_thompson5910):
good
jimthompson5910 (jim_thompson5910):
now onto 8
the factors of 8 are ???
OpenStudy (anguyennn):
1,2,4,8
jimthompson5910 (jim_thompson5910):
which is a perfect square?
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OpenStudy (anguyennn):
√4
jimthompson5910 (jim_thompson5910):
so we can say 8 = 4*2
jimthompson5910 (jim_thompson5910):
then use that rule
OpenStudy (anguyennn):
√8= √4x2
=√4x√2
2√2
jimthompson5910 (jim_thompson5910):
so,
\[\Large \sqrt{18}+\sqrt{50}-\sqrt{8}\]
is the same as
\[\Large 3\sqrt{2}+5\sqrt{2}-2\sqrt{2}\]
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jimthompson5910 (jim_thompson5910):
we can replace all the square root of 2 terms with x
\[\Large 3\color{red}{\sqrt{2}}+5\color{red}{\sqrt{2}}-2\color{red}{\sqrt{2}}\]
\[\Large 3\color{red}{x}+5\color{red}{x}-2\color{red}{x}\]
OpenStudy (anguyennn):
correct
OpenStudy (anguyennn):
is that the answer?
jimthompson5910 (jim_thompson5910):
not yet
OpenStudy (anguyennn):
would you do 3+5-2 now?
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