Comments on: Where to get algebraic help?
http://ask.metafilter.com/263754/Where-to-get-algebraic-help/
Comments on Ask MetaFilter post Where to get algebraic help?Tue, 17 Jun 2014 20:01:42 -0800Tue, 17 Jun 2014 20:06:07 -0800en-ushttp://blogs.law.harvard.edu/tech/rss60Question: Where to get algebraic help?
http://ask.metafilter.com/263754/Where-to-get-algebraic-help
I am working through the <a href="https://mooculus.osu.edu/">mooculus calculus one mooc</a> as a refresher (which I clearly need), and there is one thing I have run across that I just don't see. Can you help me figure out what is going on, and what I can do to work out future problems? <br /><br /> <a href="http://www.youtube.com/watch?v=daKVqDF8hng&t=7m0s">In the video on Inverses of Functions, at about 7:00</a>, the professor simplifies:<br>
<br>
(6 +/- sqrt(6^2 - 4(-12 + h/5))/2<br>
<br>
to<br>
<br>
3 +/- sqrt(9 + 12 -h/5)<br>
<br>
and I just can't see how that is done. What is confusing me is the term "+12 - h/5" in the simplified square root. It seems to be off by a factor of two, since the -4/2 = -2, not -1. What am I missing in this case?<br>
<br>
In addition, I am going to be working through this over the next weeks and have no doubt I will run into similar problems. Is there a website or software that will perform this type of simplification and show the steps? I have access to Matlab and Mathematica, but have never used them, if they help.post:ask.metafilter.com,2014:site.263754Tue, 17 Jun 2014 20:01:42 -0800carpographeralgebrasimplificationBy: peacheater
http://ask.metafilter.com/263754/Where-to-get-algebraic-help#3830367
The 2 in the denominator is out of the square root. Thus when you take it into the sqrt you get 4 not 2. <br>
<br>
To be more explicit: <br>
<br>
(6 +/- sqrt(6^2 - 4(-12 + h/5))/2<br>
=(3 +/- sqrt(36/4 - 4/4(-12 + h/5)))<br>
=3 +/- sqrt(9 + 12 -h/5)comment:ask.metafilter.com,2014:site.263754-3830367Tue, 17 Jun 2014 20:06:07 -0800peacheaterBy: empath
http://ask.metafilter.com/263754/Where-to-get-algebraic-help#3830372
6^2 - 4(-12 + h/5) =<br>
<br>
36 +48 +4h/5<br>
<br>
Divide it through by 2^2, basically, since it's inside a square root.comment:ask.metafilter.com,2014:site.263754-3830372Tue, 17 Jun 2014 20:08:55 -0800empathBy: peacheater
http://ask.metafilter.com/263754/Where-to-get-algebraic-help#3830373
I realize that I may not have made it super clear above what I mean by taking something into a sqrt. Imagine that the numerator is anything within a square root. For example: <br>
sqrt(6)/2<br>
<br>
This can be rewritten as sqrt(6)/sqrt(4) (since 2^2 is 4). Since both the numerator and denominator are under sqrt, we can rewrite this as sqrt(6/4) = sqrt(1.5). <br>
<br>
It's exactly the same logic that operates above, it's just a bit more complicated numerically.comment:ask.metafilter.com,2014:site.263754-3830373Tue, 17 Jun 2014 20:09:50 -0800peacheaterBy: carlypennylane
http://ask.metafilter.com/263754/Where-to-get-algebraic-help#3830393
you can try looking on <a href="https://www.khanacademy.org/">Khan Academy</a> to see if they have videos that are relevant for you. They have a ton of math and science videos as supplements to a topic, and they're usually short and easy to understand. worth a look!comment:ask.metafilter.com,2014:site.263754-3830393Tue, 17 Jun 2014 20:54:28 -0800carlypennylaneBy: bluekazoo
http://ask.metafilter.com/263754/Where-to-get-algebraic-help#3830482
Seconding the bit about Khan Academy, but also adding that the site also has a section where you can do exercises and get immediate feedback on whether or not you got them correct. The videos are definitely worth a look too and are generally clearer most of my math teachers/professors in high school and college.comment:ask.metafilter.com,2014:site.263754-3830482Wed, 18 Jun 2014 00:53:28 -0800bluekazoo