The Unofficial Homework Help Thread

looking for an explained work flow for these two equations.

10/(x−2) ≥ x−5

(im most of the way through this one i just dont know where to go after 5x/ (x-2) ≥ x to get the x on the other side. Im just doing circles right now and wolfram alpha is no help because it doesn't show the steps or what you actually are supposed to do.

and this one

|x + 7| = |2x + 1|

I havent done math in like 2 years and im doing a first year calc course so im just trying to get my bearings again. Im getting help from a buddy tomorrow with these but for now i thought i would add to this thread with a real question.

If somebody actually helps me out i will be more than grateful. Il owe you.

 
The asymptote can fuck you up because it changes from negative to positive without crossing the x axis, hence solving as if it were an equal sign will not give you all of the info. This one is easy to do in your head, but this is the "right" way.

\frac{10}{x-2}\geq x-5

\frac{10}{x-2}-(x-5)\geq 0

\frac{10-(x-2)(x-5)}{x-2}\geq 0

\frac{x^2-7x}{x-2}\geq 0

\frac{x(x-7)}{x-2}\geq 0

link: http://physicsstudy.wordpress.com/2012/09/22/usually-you-can/

now just solve the top of the fraction for zero to get your x intercepts, the bottom of the fraction to get your asymptote and then determine if the function is negative or positive in the four regions these points split up.

note that if you ever get this in everyday life it is much easier to just note the asymptote is at x=2, and the multiple the RHS by (x-2) to quickly solve it with no work.

 
wow thanks a ton dude! that helped a ton. I was just doing one thing wrong but i understand it way better now.

Stoked.
 
No worries man. Good luck with calculus!

It's good to be reviewing precalc like this. Make sure you have that, especially trig, on lock. All of the calculus in calc 1 is easy. The precalculus stuff is what will kill you.

 
is anyone here good with circuts? I feel stupid but I cannot remember how to find the net resistance from a to b here:

568041.png
 
Resistors in Series:R(eq) = R(1) + R(2) + .... R(i)

Resistors in Parallel:

R(eq) = [R(1)^-1 + R(2)^-1 + .... R(i)^-1]^-1

Is that what your looking for?
 
I'm not really familiar with any other way to find net resistance in a circuit with just the information you supplied.

Did they give you the potential or at least any other info?

 
physics.

It's a dumb class because nothing is derived. So I have to memorize all these theorems. This one should be basic though and I still can't get it.

I'm thinking I might just put a voltage source on this and tackle it the long way.
 
nope, but I figured it out using a brute force technique. It was a pain in the ass. I drew in a voltage source and then used kirchoff's laws to come up with a 6x6 system of linear equations which I solved to get the current leaving my voltage source so I could finally find the resistance across that network.

I think the whole point of this course Is so I don't have to do shit like that. There must be an easier way but I eventually just said "fuck it" and did it the long way.
 
Anyone know a good website for a graphing calculator with a table of values option? I need one that will automatically put y's when i put in x's.
 
wait so you have a function y=f(x) and just want a table of values showing the values of x and y for user defined x values?

you can do this on basically any spreadsheet or graphing program...
 
can anyone help me with writing a Lincoln Douglas style debate case? or just any tips about debate would be helpful
 
It's a super dry subject, but I will shower karma to whomever can write me up a brief description of the Great Awakening in early America in regards to John Edwards.

Anything will help!
 
I need a scientific essay (4-5 pages). Doesn't really matter what it's about. Needs to be in english.

Thanks
 
Shit, I think there is a trick to doing circuits like this but I can't remember. I know the kirchoffs laws and loop laws and whatever work, as you found out. But having to solve for 11021923 different variables is not fun.

I think I'm thinking if it was a capacitor in the center, cause there's a trick to that depending on how it's charged.
 
well actually no, I have not taken AP physics, and yes I know how to do those problems.

also thanks DrZoidberg, I have since found out how to solve this problem in a simpler way!
 
It's not the matrix for solving the equations the kirchoff laws and whatever is it? Cause when I learned that I was just like no thanks, I'll stick with the normal equations. Granted the matrix is better for larger systems, but it's annoying as hell.
 
you could use any mathematical technique you want to solve it, but yeah I used a matrix. 6 equations and 6 unknowns would be such a bitch without it. I know some linear algebra though so I used cramers rule since I only needed to solve for one variable.

but what I have sense found out is how to use thevinin's theorom to solve this more easily.
 
it's a 5 page paper on any subject you want. You should be able to hammer that out in an hour and a half.
 
Bumping this if anyone here can help me with Centroids and Center of Masses that would be fucking great!

I'm just staring at my assignments with no clue how to do them...
 
centroid.jpg


red = midpoints ---- orange = midpoint->opposite vertice ---- blue = centroid

centroids are the midpoints of all 3 sides conected to the opposite vertice.

midpoint formula is ([x1+x2]/2) , ([y1+y2]/2)

find the midpoint of all 3 sides and connect it to the opposite vertice. (i.e opposite BC = A)

midpoint AC = ([0+8]/2) , ([0+0]/2) or (4,0)

midpoint AB = ([0+4]/2) , ([0+2]/2) or (2,1)

midpoint BC = ([2+8]/2), ([4+0]/2) or (5,2)

connect each midpoint to the opposite vertice and the point at which they intersect is the centroid of the triangle.

centroids=balance points (center of masses)

hope this helped
 
That works great for shapes such as triangles but the problem i had was y=e^x y=0 x=0 and x=3.

+k for trying to help though! I appreciate the effort!
 
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