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Calculus1 17 Online
OpenStudy (anonymous):

I need help with simplifying

OpenStudy (anonymous):

\[6a \sqrt{80b}-\sqrt{180a ^{2}b}+5a \sqrt{b}\]

OpenStudy (jhannybean):

Look at the middle term and take the prime factorization of 180

OpenStudy (jhannybean):

Do the same for 80

OpenStudy (anonymous):

60 & 2 for 180 then 40&2 for 80 right?

OpenStudy (jhannybean):

\[6a\sqrt{20\cdot 2 \cdot 2 \cdot b}- \sqrt{20 \cdot 9 \cdot a\cdot a \cdot b}+5a\sqrt{b}\]

OpenStudy (jhannybean):

\[60 \cdot 2 \ne 180\]

OpenStudy (anonymous):

lol i had meant 90

OpenStudy (jhannybean):

Yes that works too :)

OpenStudy (jhannybean):

now factor both 20's and the 9 into simpler, prime factors.

OpenStudy (anonymous):

10 x 2 for 20's & 3 x 3 for 9

OpenStudy (jhannybean):

Good. \[6a\sqrt{10\cdot 2\cdot 2 \cdot 2 \cdot b}- \sqrt{10 \cdot 2 \cdot 3\cdot 3 \cdot a\cdot a \cdot b}+5a\sqrt{b}\]

OpenStudy (jhannybean):

factor both 10's one more time into prime factors.

OpenStudy (anonymous):

5 & 2

OpenStudy (jhannybean):

Great \(\checkmark\) \[6a\sqrt{5\cdot 2\cdot 2\cdot 2 \cdot 2 \cdot b}- \sqrt{5\cdot 2 \cdot 2 \cdot 3\cdot 3 \cdot a\cdot a \cdot b}+5a\sqrt{b}\]

OpenStudy (jhannybean):

Now for every fair of 2 numbers, 1 of them will be extracted from the square root and multiplied to the term outside the square root.

OpenStudy (jhannybean):

pair*

OpenStudy (jhannybean):

For example, to start you off. \[6a\sqrt{5\color{blue}{\cdot 2\cdot 2}\color{red}{\cdot 2 \cdot 2} \cdot b} = 6a \cdot \color{blue}{2} \cdot \color{red}{2}\sqrt{5 \cdot b}\]

OpenStudy (anonymous):

\[48a \sqrt{5\times2timesb}-6a \sqrt{5\times2\times3 \times a \times b}+5a \sqrt{b}\]

OpenStudy (jhannybean):

Not quite. In the first part you still have a 2 left within the square root when its been paired off and pulled out already. You should just have a 5 and a b left within the square root there since they are lone pairs and cannot be pulled out. Once things are paired off, they are not rewritten within the square root. Second part, the 6a looks right, therefore the only thing that should be left within the square root should be 5 and b.

OpenStudy (anonymous):

ohh okay i think i got it now

OpenStudy (jhannybean):

It should look like this: \[6a\sqrt{5\color{blue}{\cdot 2\cdot 2}\color{red}{\cdot 2 \cdot 2} \cdot b} = 6a \cdot \color{blue}{2} \cdot \color{red}{2}\sqrt{5 \cdot b} = 24a\sqrt{5b}\]\[- \sqrt{5\cdot\color{red}{ 2 \cdot 2} \cdot \color{blue}{3\cdot 3} \cdot \color{green}{a\cdot a} \cdot b} = -6a\sqrt{5b}\]

OpenStudy (anonymous):

yeah thats what i got

OpenStudy (anonymous):

|dw:1441173348642:dw|

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