LIMIT RULES:
1. if the degree of the top is larger than the degree of the bottom, the limit approaches infinity
2. if the degree of the bottom is larger than the degree of the tip, the limit approaches zero
3. if the degree of the bottom is equal to the degree of the top, then you make a fraction out of the coefficients in front of the largest degree
So for implicit derivatives...its pretty easy. You are going to be using this when you have like y^2 + x^2 = 4. It will ask for dy/dx. So what you do is you take the derivative like normal...but whenever you take the derivative of y you write dy/dx. So the above would be 2y (dy/dx) + 2x = 0. Now you solve for dy/dx. To do this, minus over 2x and then divide by 2y. So the answer would be
dy/dx = -x/y.
Some people have been asking about related rates!!!!!!!!!!!!! SO HERE IS an EXAMPLE!!!
Um let's see...
The steps for related rates are:
1. Pick out all variables
2. Pick out all equations
3. Pick out what you are looking for
4. Sketch a graph and label
5. Create an equation with your variables
6. Take the derivative respecting time
7. Substitute back into the derivative
8. Solve
Okay so first derivative refers to slope of position..which is velocity.
Second derivative is slope of velocity...or acceleration.
Third derivative would be the slope of acceleration which I believe is jerk.
Past that, its just the rate of change of whatever was before...so...yeah.
Anyway, think this is around 285 words so...see you guys tomorrow.
Posted by XxDohxX at 8:30 PM 0 comments
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post of holidays..3
IMPLICIT DERIVATIVES:
1. Take the derivative like normal.
2. For each y-term, you put y' or dy/dx behind it.
3. Solve for dy/dy or y'.
36x^2 + 2y = 9
36x + 2(dy/dx) = 0
2(dy/dx) = -36x
-36x/2
dy/dx = -18x
steps to SECOND IMPLICIT DERIVATIVES
1. Take the derivative of the first derivative
2. Put d^2y/dx^2 for dy/dx
3. Simplify
4. Plug in values
so an example using the same equation is:
we take the first implicit derivative first
36x^2 + 2y = 9
36x + 2(dy/dx) = 0
2(dy/dx) = -36x
-36x/2
dy/dx = -18x
You have to identify what you are looking for and what you are given. Not only does this make it easier on you, it's kind of necessary, especially when you want those points on free response questions (or so I'm told). You also have to realize that when you are doing related rates, you have to put dy/dt or dx/dt or whatever whenever you are taking the derivative of some variable in relation to time (hence the t). So given that:
Given xy = 4
you want to know what dy/dt equals given x = 8 and dx/dt=10.
Take the derivative (product rule):
dx/dt y + dy/dt x = 0
Plug in everything:
dy/dt = -10y/8
= -5y/4
Obviously, I'm not doing perfect, and I don't know everythin, so here's my trouble areas:
1. I can't remember when to use washers and disks-and i switch up the equations.
2. Slope Fields!!!! I get the one we did on the free response,,,just none like on the practice tests..if that makes any sense.
3. my e integrating skills have something to be desired...
any suggestions?
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disks don't have wholes..so if they say a solid figure, it's a disk. This formula for area is just the integral of the equation they give you.
ReplyDeleteWashers have a whole in the figure, and you are given two equations. You use the top graph equation minus the bottom equation for area..and when you are finding the volume, you square both formulas.
lol @ stephanie's replacement of the word "hole" with "whole" :-).
ReplyDeleteAnyway, basically to elaborate on the "hole" thing a bit more. When we are are revolving an equation about an axis, there are two different methods that may be used. Basically, if your graph does not touch both the axis you are rotating about and both equations, you will be using washers. (The reason its washer is because a washer is basically a disk, with a hole in it). If your equation does touch both the axis you are revolving around and the equation, then you are most likely using disks.
A lot of the time if you have one equation it will wind up being a disk.. Two winds up being washers. However, they are worked basically the same as stephanie says. Disc is equation squared. Washer is top equation squared minus the bottom equation squared.
Ok, volume by disks is used when you're rotating only one equation or one graph. Volume by washers is used when you have two equations or graphs, sort of like area under the curve, except you are squaring both of the equations separately and multiplying the whole integral by pi.
ReplyDeletedisks don't have holes..so if they say a solid figure, it's a disk. This formula for area is just the integral. Washers have a hole in the figure. You are given two equations. You use the top graph equation minus the bottom equation for area. When you are finding the volume, you square both formulas.
ReplyDeleteSlope fields are actually pretty easy. You basically just connect the dots (or lines in this case). Just follow the lines where they "point" to. Usually straight lines indicate an asymptote.
ReplyDelete