I know a little bit of the first derivitave test.
1) take derivative
2) find critical values by setting equal to zero
3) set up intervals. ( -infinity, x; x to x;......;x to infinity)
4) choose proper values that are equivilent to infinity< n < x or x < n < x (or what ever value is between what ever possible critical values you find.
5) determine weather your answer when plugged backinto the first derivative is positive or negative. If it is positive then it is a min meaning that the slope of the graph at that point is going up. If it is negative then it is a max saying that the graph is going down and the slope is going down.
6) determine your maxs and mins by using your data that you have found.
*****7) the one that i forget to do and the one that requires writing. JUSTIFY. After problem is worked you must justify your answer by explaining what you did in writing that will be able to give enough infortion so that your first derivitive test is clear and easy to follow due to your explanation.
The problem with this test is not remembering the steps, but for me it is to actually work the problem. Most of the time i dont know what it is asking and as the GROUP KNOWS lol that packet was beast. Taking the derivitave to me is the easiest, but after that i get confused and dont understand what part to set equal to zero or how in some cases. Like when it is a fraction with a polynomial at the top and bottom, do i set both numerator and denominator to zero or just top???????
Something else that is confusing me is:
sinx-cosx
derivative: cos(x)+sin^2(x)
***Do i set this whole thing equal to zero or do i brake up the terms and set cosx equal to zero and six^2x equal to zero???This problem confused the crap out of me.
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i'm pretty sure you don't break up the terms. i think you just leave the whole thing like that and set it = to 0.
ReplyDeletewhenever you have a fraction you don't set the numerator and denomenator equal to zero. you only set the TOP equal to zero. then solve, then those are your critical values/possible points of inflection.
ReplyDelete& i know exactly what problem you are confused about. ok so you have cos(x) + sin^2(x).
the derivative would be -sin(x) + cos^2(x). Then you would set the whole thing equal to zero. you would only separate them and set equal to zero if you factored something out. Like if you had sinxcosx+sin^2(x). You would factor out a sinx and get sin(x)[cos(x)+sin(x)]. then whenever you set it equal to zero you would sin(x) = 0 and then separately set cos(x) + sin(x) = 0 because you factored out that sin(x).
Make sense? I hope so!
dont set the numerator and denominator equal to zero when you have a fraction just set the top equal to zero and then you can solve it.
ReplyDeleteI'm pretty sure you do not separate them. You just set the whole thing equal to zero.
ReplyDeleteWhen you have a fraction and need to set equal to zero, you just have to set the top equal to zero. Also when it's something like cosx - 2sinx and you have to set it equal don't split them up like you want to and set it equal, you have to set the whole thing equal to zero unless it's like cosx(sinx + 2) or something like that.
ReplyDeleteset just the numerator = to zero b/c the denominator is gonna cancel anyway
ReplyDelete