AP Calculus AB 2015 Thread

does anyone know how to separate the variables on number 4? I left it blank on the test, but if we weren’t supposed to separate the variables i know how to do it. I just didn’t put that because i thought it was too simplistic and wrong, so i left it blank

@zach1198 5D

does someone mind making a google doc now that its allowed that way its easy to identify what questions were all talking about, idk about you guys but all of this info is confusing me

I think @MathToot said he was going to.

Didn’t 4D ask for constants? So how could there be an x in the solution? ( @zach1198 ) I got m=1 and b=1, but I really didn’t know what I was doing. I think I just used the point they gave in part c, but couldn’t you have used any point and gotten a variety of answers? What is calculus???!!?!?

Does anyone know how to do 4c, where it asked if at a certain point what happens, a maximum, minimum, or neither/ It was with the slope field. I put neither but I guessed and said it was positive before and was positive still at that point.

neither

Are you sure, could you give an explanation? I appreciate it @APScholar18

@itsmyusername I got the same answer as you. My friend got an x in the answer. The whole differential equation got my confused since i was used to seeing it as dy/dx=xy not x-y.

@cocoabutter16 you evaluate dy/dx at (2,3) the value is 1 so its not an extrema at all, its slope at that point is +1

@zach1198 I got 1 and 1 I used the condition from part c and went from there in point slope form and then simplified it to y=mx+b which ended up being y= x+1

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@skieurope I’m just curious as I’m still new to CC, but is there something wrong with compiling answers to a released FR from the AP exam? Also, what’s your favorite ski resort?

Can somebody with credentials in math please do FRQ #4 and tell us what you got. Especially for part d.

Ok for 1D, the water does not overflow at t=8, so i think doing the integral from 8 to w is ok, because w would represent the time it does overfilll, so the rates would still be the same

@Kylemcgrogan Links to any non-authoritative website are not allowed per Terms of Service. If anybody wants to post the solutions on an authoritative website (like your school’s), be my guest. But no on google, tumblr, Facebook, etc.

For 1a) I wasn’t sure whether or not to add 30 to the answer and I ended up deciding not to because it says flow into and if it was there to begin with it didn’t flow into and I got an answer of like 70 something. Was I right?

@skieurope Ok, thank you for clarifying

Can anyone please tell me how much they think 1a, 1b, 3a, 3b, 3c, and 4a are each worth?

For 5D I believe I said f(-2) was 12 and f(4) was -9.