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Mathematics 18 Online
OpenStudy (anonymous):

What is the simplest form of the radical expression?

OpenStudy (anonymous):

\[\frac{ \sqrt{2}+\sqrt{5} }{ \sqrt{2}-\sqrt{5} }\]

OpenStudy (anonymous):

well you cant really have a whole number for the square root of these two numbers. the best thing we could do is round the decimal. so the square root of 2 is about 1.41 and the square root of 5 is about 2.24. if we had those two together on the top, we would get 3.65.

OpenStudy (anonymous):

then if we subtract those two, we would get -0.83.

OpenStudy (anonymous):

now did you want the two answers divided or into a fraction?

OpenStudy (anonymous):

it says i need to get them in simplest form and show work but it can't be rounded. it must be exact

OpenStudy (anonymous):

oh. maybe we would round the decimal to a whole number then

OpenStudy (anonymous):

I'm pretty sure they want you to multiply by the conjugate. Give me a minute to work it out then I'll explain.

OpenStudy (anonymous):

that makes no sense :( i am not supposed to round this ever

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

i know the answer will likely still have square roots but be simpler?

OpenStudy (anonymous):

maybe you just need someone else

OpenStudy (anonymous):

jam is replying. he helped me really well. let him take over

OpenStudy (anonymous):

sorry for not helping. :/

OpenStudy (anonymous):

When you are dealing with radicals, they don't like to see them in the denominator. Conjugate example. 1 + sqrt2 has a conjugate of 1 - sqrt2 So for this question, multiply top and bottom by sqrt2 + sqrt5. That's what I think they want you to do.

OpenStudy (anonymous):

(sqrt2 + sqrt5) / (sqrt2 - sqrt5) times (sqrt2 + sqrt5) / (sqrt2 + sqrt5) = (2 + 2(sqrt5)(sqrt2) + 5) / 2 - 5 = [7 + 2(sqrt5)(sqrt2)] / (-3) = [-7 - 2(sqrt5)(sqrt2)]/3 That's what I think the answer is.

OpenStudy (anonymous):

\[-\frac{( \sqrt{2}+\sqrt{5} )^2}{ 3 }\] is how it comes up for me, is this right?

OpenStudy (anonymous):

my answer makes no sense at all

OpenStudy (anonymous):

That's exactly what I got. I just multiplied out the top.

OpenStudy (anonymous):

what?

OpenStudy (anonymous):

where did the 7+2 part come from?

OpenStudy (anonymous):

or -7-2

OpenStudy (anonymous):

sqrt2 times sqrt2 = 2 sqrt5 times sqrt5 = 5

OpenStudy (anonymous):

simpler example: I'll draw:

OpenStudy (anonymous):

Do you see how to expand these sort of expressions?

OpenStudy (anonymous):

\[(3+\sqrt{2})\times(3+\sqrt{2})=93+\sqrt{2}+3\sqrt{2}+4=9+6\sqrt{2}+4=13+3\sqrt{2}\] is this what you wrote?

OpenStudy (anonymous):

\[(3+\sqrt{2})\times(3+\sqrt{2})=93+\sqrt{2}+3\sqrt{2}+4=9+6\sqrt{2}+4=13+6\sqrt{2}\] so this then?

OpenStudy (anonymous):

its hard to read, so just tell me if this is what you meant to write

OpenStudy (anonymous):

Let me start over. There were a couple of mistakes in mine.

OpenStudy (anonymous):

use the equation button pls

OpenStudy (anonymous):

Thanks for telling me about the equation button. I didn't know about it. Do you see how to expand the brackets now? root 2 times root 2 equals 2.

OpenStudy (anonymous):

\[(3 + \sqrt{2}) \times (3 + \sqrt{2}) = 9 + 3\sqrt{2} + 3\sqrt{2} + 2\]

OpenStudy (anonymous):

\[9 + 2 + 3\sqrt{2} + 3\sqrt{2} = 11 + 6\sqrt{2}\]

OpenStudy (anonymous):

That's how I expanded the original question.

OpenStudy (anonymous):

Now I'll type in the end of your solution.

OpenStudy (anonymous):

\[(\sqrt{2} + \sqrt{5}) \times (\sqrt{2} + \sqrt{5}) = 2 + \sqrt{2}\sqrt{5}+\sqrt{2}\sqrt{5} + 5\]

OpenStudy (anonymous):

So that's what is on top and there's a -3 in the denominator. I gathered like terms and moved the minus sign up to the numerator to get:

OpenStudy (anonymous):

\[(-7 - 2\sqrt{5}\sqrt{2})\div3\]

OpenStudy (anonymous):

OS keeps freezing up on me for some reason, I think I can piece together an answer from the information given. Thanks for bearing with me.

OpenStudy (anonymous):

No problem. Your answer was right. I think they would want you to expand the numerator instead of leaving it squared. So that's what I did.

OpenStudy (anonymous):

Do you want me to attach a file with the whole thing written out? It might be clearer that way?

OpenStudy (anonymous):

I can't attach it right now. Problems with my scanner. I'll try again later.

OpenStudy (anonymous):

alright, thanks @jam333

OpenStudy (anonymous):

OpenStudy (anonymous):

My answer could be wrong, but I think that's what they want. What level of school are you in? It helps so I know what to send you. I can send reviews of important concepts.

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