Free Math Help - Page 4

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United States10328 Posts

September 04 2011 15:12 GMT

#61

On September 04 2011 23:25 Adeny wrote:
Hello! Quick question: How does this work: http://www.wolframalpha.com/input/?i=(3a^2b) / (6ab^2)

I.E. how would you go about solving it step by step?

You're not solving anything (there's no equal sign)... but to simplify, cancel a, b, 3 from top and bottom.

@the integral above: weird, I don't see any non trig sub way that works.

Zortch

Canada635 Posts

September 04 2011 16:10 GMT

#62

On September 04 2011 19:42 targ wrote:
Nice thread! I'm doing an online math course at the moment, and would appreciate any help on one question.

How do I get the integral of 5(1 + x^2)^1/2 ? I checked with my friend and Wolfram Alpha, and they both used trigonometric substitution. However since this question appeared the first chapter of integration, where trigonometric substitution was not taught yet, I feel that there might be an easier way to get the answer. Any ideas?

Some texts have integration "rules" for dealing with stuff like this in early chapters. The rules are just what you get if you did the trig substitution. Then once you get to trig substitutions you don't need the rules anymore as you can do the substitution. Could be a case of that kind of thing?

krndandaman

Mozambique16569 Posts

September 04 2011 19:00 GMT

#63

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blankspace

United States292 Posts

September 04 2011 21:20 GMT

#64

sometimes even though f is not injective, people write f^-1(x) to mean the preimage of x, that is the set of points in the domain that map to x.

so here you just need to do -x^2 -2x + 3 = -3, or solve x^2+2x-6 = 0. You get some irrational roots.

krndandaman

Mozambique16569 Posts

September 04 2011 21:52 GMT

#65

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tryummm

774 Posts

September 05 2011 19:10 GMT

#66

I am in Calculus #2 and I am having trouble finding the shapes of the cross sections when using the washer method, disk method, etc... and rotating it around the x/y axis. I also have some problems figuring out which volume equation to use, but that's in part because of my difficulty finding the cross sections.

This is chapter 6.2-6.3 of CALCULUS E A R LY T R A N S C E N D E N TA L S
SIXTH EDITION by James Stewart.

I was wondering if anyone had any advice or knew of any guides online on visualizing the shapes of the cross sections for various functions to solve for the volume.

Thanks a lot, I appreciate it.

sur_reaL

Canada278 Posts

September 05 2011 20:17 GMT

#67

damn tryummm, I got the solutions book for that right here sitting on my desk. It's a friends but I can't buy it from her since my course requires a different book and being a first year, I don't understand any of it...

FortyOzs

189 Posts

September 16 2011 03:36 GMT

#68

I have to differentiate the equation 8^t - 5^t / t, and how should i differentiate it? Do I take the natural log of the whole thing and can I do it separately for both 8^t and 5^t

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