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Message: for 11.1 #10, what happens after we get (1/3)(y^3)- (1/2)(y^2)=(1/2)(x^2)+C?
Reply: You can just circle it since you can't easily solve for y.
Message: on the fall exam, problem 4, is the question wrong? f(x)=x-cosx would mean f'(x)=1+sinx, but it says f'(x)=-1+sinx?
Reply: Sorry! There was a typo that was corrected during the exam and I was sent the original from the professor so I forgot about the change. The correct version of the problem is the one in the solutions.
Message: fall and practice problem solutions give "404" messages?
Reply:Sorry! I was in the process of uploading them but then I had to leave to eat dinner. They'll be up within the next ten minutes.
Message: how do we even do 11.1 #10? i'm so lost.
Reply: It's separable so get all y's to one side and all x's to the other.
Message: So we have a quiz on Monday? could we not have one because it takes so much time? And then we could review more? please??
Reply: I'll make the quiz short. As of now we have three full class days for review which is one more than I had originally planned.
Message: where do we split the integral for 8.4 #4?
Reply: I'm not sure what you mean. There is no split but the integral has infinity as its upper bound so you have to use limits for it.
Message: how do we even start 8.2 6 homework???
Reply: Sorry for the late reply! I'm in the process of moving. To do this problem, first rewrite the integral as the integral of (1-x)1/3e^(-x) and then do integration by parts.
Message: Problem 4 Fall 2016 review: I do not understand why cos(pi/2)+(pi/2)=pi/2. Could you explain this? Thank you.
Reply: cos(pi/2)=0
Message: If we're given a defined function with an interval of [a,b], would we say it's increasing on [a,#], or is it (a,#)? (parentheses or bracket?)
Reply: I personally use (a,b) for intervals dealing with critical numbers. On the practice exam I put brackets because it was a restricted interval so the bracket end points werent critical numbers. On the midterm for tomorrow I did write "open intervals" in the instructions to clarify that you should use parenthesis.
Message: 7.2 #60, do you want us to go through the two ways and solve both? or how do we answer?
Reply: The two got two answers doing perfectly correct work for the same integral so the answers should be equivalent. I want you to explain why they are. In other words why is (x^2+2)^2/2+C the same as x^4/2+2x^2+C?
Message: what's 7.4 homework? i don't think i can see it. :(
Reply: Sorry! I just got home. It's up now!
Message: What time do you normally show up to your office in the morning because I really need extra help on homework and revisions.
Reply: I'll be on campus tomorrow around 8 because I'm carpooling but after that I'll probably be getting to campus around 9:45.
Message: it's me again. it'd be nice to have the answers earlier, but i don't want to rush you!
Reply: Sorry! Didn't see this until now. I'll start working on them. Hopefully they'll be up by tomorrow morning.
Message: hi! when are you going to post the answers to the practice exams and problems?
Reply: I was planning on posting them by tomorrow night. I can work on posting them sooner if needed.
Message: 7.2 34: So u is log(2)(5x+1)?
Reply: That sounds like a great choice to me! :)
Message: 7.2: #34: How do we integrate log(base2)x?
Reply: This is a u-sub problem so the real question you should ask yourself is how do you differentiate log(base2)x. This was a rule given back when you learned differentiation so you can find it in your notes or the book.
Message: homework still not showing?: it's still blank on friday.
Reply: Have you refreshed the page? My page shows homework.
Message: is there going to be homework?
Reply: Sorry! I thought I posted it. It should be up now.
Message: 5.3 52: i really don't get why there are three important points? i can only find two?
Reply: Important numbers are where the second derivative zero or undefined. There should be two for where it is zero and one for where it is undefined.
Message: will there be webwork for 5.3?
Reply: Just updated it!
Message: I just noticed there's the derivative of cotx twice on the reference sheet, and one of them is supposed to be cscx
Reply: Thank you! I'll update the website copy and the midterm.
Message: webwork 4.4-4.5, #2: how do we input log base 8?
Reply: Sorry! Webwork doesn't accept log_8(x) as a function but it does accept lnx so you need to do a change of base when you want to write log base 8. Use log_8(x)=(lnx)/(ln8).
Message: for 4.1 webwork: i don't understand problem 2? there's no way to calculate x if x is supposed to be a real number.
Reply: I'm unsure what you mean. The problem gives you a function and wants to know what point that line is tangent to. The line it gives has slope 6 so what you have to do is calculate the derivative of the function that is given and set it equal to 6. When you solve for x you will get two nice values for where the tangent line has slope 6. Then you can use the equation of the tangent line to determine which x value is the right one.
Message: spring midterm: i don't get how to do the fifth problem on the spring midterm? how do we factor cubic equations? did we talk about maximums and minimums?
Reply: Haha don't worry about number 5. We haven't covered that section yet! :)
Message: Math 215 Midterm 1 Sample Problems: For the second one, is the piecewise function written correctly? Is one of the x conditions supposed to be -1 instead of 1?
Reply: Yes! The first condition should say x<-1. Thank you for letting me know!
Message: 4.5 question 64: I was just wondering if you could tell me if I got the correct derivative.
Original P(t)=30.60-5.79(ln t). Steps P'(t)=0-0(ln t)+5.79 (1/t). Final P'(t)=5.79(1/t). Getting a little confused, thank you.
Reply: Yup all your steps look correct! Just so you know, you don't have to do the product rule for 5.79(lnt). You could use the constant multiple rule instead.
Message: Webwork: For 4 and 5 on 3.4, I don't really get what we're supposed to put in the first two boxes?
Reply: Sorry! I didn't realize that the question was worded strangely. What is wants is for you to use the second limit definition of a derivative i.e.. lim_{x->b}(f(x)-f(b))/(x-b).
Message: May come drop off my rewrite today? I'm still on campus and pau with rewrite.
Reply: I'm about to leave but in general, you can find me in Keller 418 from 8am-2pm (not including class time of course).
Message: Thanks for answering! But for 1.3 #14, when I put in that answer, I get this: "incorrect Can't generate enough valid points for comparison"
Reply: Try to use sqrt(u) instead. If that doesn't work then I can look at it tomorrow if you're comfortable with that.
Message: Will the quiz only be on the review section or will it include everything up to 2.4?
Reply: Everything up to 2.4
Message: For #14 (1.3) on Webwork, why isn't (c) y=9/u^(1/2)
Reply: It should be. I just checked and WebWork accepted that answer for me.
Message: For #5 (1.1) on Webwork, why isn't m=undefined?
Reply: It is! It's just that the problem doesn't accept that as an answer so you have to type in "does not exist". This is one of the reasons I'm not making WebWork worth points.
Message: 2nd Assignment: The link won't work.
Reply: Sorry! I added the link before I scanned the pages because I didn't expect anyone to check the website in those few minutes haha. It will be updated in the next five minutes.
Message: This is a great website professor! thanks for making it so simple and easy to use.
Reply: No problem! Let me know if you have any questions/concerns!