/sci/ - Science & Math

So my fellow CS/CE fags.

What encouraged you to take up this field of study ?

ITT post a fact that blew your mind when you first heard it. Doesn't matter what field of science it's from or how basic it is. Go /sci/entists.

Bumping

>>3075095
They are usually numbered off in the 4chan file name format in my folder. So i rename them whatever in order to find them when I upload them.

Alright, I would like some assistance. Just took a test in AP Calc. We're currently working on rates of change. This one word problem has me confused. Theres a tringle with height that is changing at a rate of 3cm/minute. The surface area changes at a rate of 2cm^2/min. What is the rate of change of the base of the triangle when the surface area is 90cm^2/minute, and the height is 10cm?
Well, using A=1/2hb, I got the base to be 18cm at this point. So, derivative time.
A*da/dt=1/2*h*dh/dt*b*db/dt.
Substitution time.
90*2=1/2*10*3*18*db/dt
This gives 180=270db/dt
So the rate of change for the base is 2/3cm/minute, but my teacher says the answer is -5cm/minute. Either I'm messing up here, the teacher is smoking crack, or else I misread the question. Most of the class got -5cm/min, but I and one other got 2/3cm/min.
Any thoughts? Remember, I am just trying to copy the word problem as best I can...but all the numbers I supply are correct.
wallpaper for your time