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Mathematics 21 Online
OpenStudy (anonymous):

sr6 x sr5

jimthompson5910 (jim_thompson5910):

Hint: use the idea that \[\Large \sqrt{x}\sqrt{y}=\sqrt{xy}\] In plain English, this says that when you multiply two square roots, you can multiply the stuff inside the square roots and you'll get the same answer For example \[\Large \sqrt{2}\sqrt{3}=\sqrt{2*3}=\sqrt{6}\]

OpenStudy (anonymous):

what if there is exponents for example 3sr2x3sr3

OpenStudy (anonymous):

\[\sqrt[3]{2}\sqrt[3]{}\]

jimthompson5910 (jim_thompson5910):

oh you mean cubed roots?

OpenStudy (anonymous):

yes

jimthompson5910 (jim_thompson5910):

same applies \[\Large \sqrt[3]{x}\sqrt[3]{y} = \sqrt[3]{xy}\]

jimthompson5910 (jim_thompson5910):

so for instance, \[\Large \sqrt[3]{5}\sqrt[3]{6} = \sqrt[3]{5*6}=\sqrt[3]{30}\]

jimthompson5910 (jim_thompson5910):

this works for any nth root for that matter

OpenStudy (anonymous):

ok thank you, if theres a variable attatched to the sr is it still the same process?

jimthompson5910 (jim_thompson5910):

yes this works for any real numbers (and variables are just unknown numbers)

OpenStudy (anonymous):

\[\sqrt{7p/6}\sqrt{5/q}\]

jimthompson5910 (jim_thompson5910):

same idea also applies to fractions so multiply the fractions to get \[\Large \sqrt{\frac{7p}{6}}\sqrt{\frac{5}{q}}=\sqrt{\frac{7p}{6}\times\frac{5}{q}}=\sqrt{\frac{35p}{6q}}\] So \[\Large \sqrt{\frac{7p}{6}}\sqrt{\frac{5}{q}}=\sqrt{\frac{35p}{6q}}\]

OpenStudy (anonymous):

ha its amazing how simple math is once it is properly explained, once again thank you

jimthompson5910 (jim_thompson5910):

yw

OpenStudy (anonymous):

\[f(x)=\sqrt[3]{40x^6}\]

jimthompson5910 (jim_thompson5910):

and what do you want to do here?

OpenStudy (anonymous):

oh sorry, find a simplified form of f(x) assume x can be any real number

jimthompson5910 (jim_thompson5910):

now you're going in reverse of what you've been doing before So factor 40 into 8*5 and factor x^6 into x^3*x^3 Doing this gives us \[\Large \sqrt[3]{40x^6}=\sqrt[3]{8*5*x^3*x^3}\] Now break up the cubed root \[\Large \sqrt[3]{40x^6}=\sqrt[3]{8}*\sqrt[3]{5}*\sqrt[3]{x^3}*\sqrt[3]{x^3}\] and take the cube root of 8 and x^3 to get 2 and x respectively, giving us \[\Large \sqrt[3]{40x^6}=2*\sqrt[3]{5}*x*x\] Now just rearrange and multiply the terms to get \[\LARGE \sqrt[3]{40x^6}=2x^2\sqrt[3]{5}\]

jimthompson5910 (jim_thompson5910):

Let me know if you need to me go over that again

OpenStudy (anonymous):

oh ok that makes sense.

OpenStudy (anonymous):

explain how you could convince a friend that

jimthompson5910 (jim_thompson5910):

best way to confirm your answer is to use a graphing calculator

OpenStudy (anonymous):

\[\sqrt{x^2-16} greater than or equal \to \sqrt{x^2}-\sqrt{16}\]

jimthompson5910 (jim_thompson5910):

if the two expressions make the same exact graph and produce identical tables, then the two expressions are equivalent

jimthompson5910 (jim_thompson5910):

oh this is a different problem?

OpenStudy (anonymous):

yes sorry i hit post before attaching the problem so confirm your answer to a friend part were the instructions to the problem i just posted

jimthompson5910 (jim_thompson5910):

ok

jimthompson5910 (jim_thompson5910):

you can also use a graph here

jimthompson5910 (jim_thompson5910):

graph the left hand side sqrt(x^2-16) as one equation and sqrt(x^2)-sqrt(16) as another equation

jimthompson5910 (jim_thompson5910):

make the first graph a curve you can easily tell the difference from the second

jimthompson5910 (jim_thompson5910):

after you've plotted the two graphs together, you'll see that the first curve is always above the second

OpenStudy (anonymous):

im not to sure how id go about graphing that

jimthompson5910 (jim_thompson5910):

if you have a TI 83 or 84, type into y1 sqrt(x^2-16) and type sqrt(x^2)-sqrt(16) for y2

jimthompson5910 (jim_thompson5910):

the sqrt key is on your calculator

OpenStudy (anonymous):

got it. much appreciated

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