SRL Archive - Mathematics

Calculus with reward


Main

2010-03-09 17:34:47

*Reward 1 pin for most got it right before tommor 8am est*

Diddy Kong

2010-03-09 18:37:04

Answer: 4 รท 0 … OH SH*T!

Main

2010-03-09 18:39:42

this is serious man, please help me out here.

Brain

2010-03-09 18:56:11

well lets see…for the first one, take the derivative, and set it to 0, then solve for x

man, this stuff is lame without just having learned it…can't remember much of it.

XcanadamanX

2010-03-09 18:58:23

for the first one i get 0 as the horizontal tangent

Brain

2010-03-09 18:59:14

0 is one of the horizontal tangents, but just from my glance I would say there is at least one more.

XcanadamanX

2010-03-09 19:08:43

im just going by my crappy calculus software…the one thing canadian i am not proud of :P

Main

2010-03-09 19:13:47

what are you in uwo for? life sci?

XcanadamanX

2010-03-09 19:27:30

who's in uwo? im at mac for eng

Nava2

2010-03-09 21:26:01

I'm at UWO for eng. Currently life sci though. :(

Close though ;)

HyperSecret

2010-03-10 01:40:43

From: Main_Ftw
*Reward 1 pin for most got it right before tommor 8am est*


I don't have the time to solve them sorry.

A) you will take the derivative of each. d[x^3y^2] + d[4(3x-2y)^3]=d[4y]-d[6x]

d=derivative, you will need to use the product rule on the first, chain rule on the second and the other side is simple.

B) The same thing as A, take the derivative of each operand.

I would have to review for the rest, sorry. I Just don't have that time right now.

ZephyrsFury

2010-03-10 06:35:09


I havent' checked question 2 and I've got the working if you want it (its rather messy though).

Main

2010-03-10 19:01:03

can you show me your steps ? :f:

ZephyrsFury

2010-03-11 05:29:06

Ok..

1. Horizontal tangents when dy/dx = 0,
Find the first derivative function.. simplies to this:

dy/dx = 4^(4x+3).x^2.(3 + 4ln(4).x)

Set dy/dx to 0 and solve for x; only ways to get 0 is if x^2 = 0 or (3 + 4ln(4).x) = 0 as an exponential function can never equal 0.

Hence,

x = 0, x = -3/(4ln(4))

Then you substitute those values into your initial function to get y and since slope = 0, there is no x value in those equations just the y value.

2. Implicitly differentiate them… too hard to explain online tbh =/

3. Again implicitly differentiate and rearrange to get dy/dx = everythingelse. You're giving the value of x = 1, so subsitute that into your y = equation to get the y values, then substitute the sets of coords (you get two y values: (1, 6) and (1, -4)) into your dy/dx function to get your gradients at those points. Then its a simple matter of finding your tangent equations.

4. Key Point: If two lines are perpendicular then their gradients multiply to -1, ie

m1.m2 = -1.
You have two functions, you can differentiate both of them in terms of x to get your gradient function in terms of x. Then multiply them together (the two functions) and set that equal to -1. Then solve the equation for x.

Main

2010-03-11 06:42:50

ty. First one was the one i didn't get, i got 0 but when i graphed it, it was totally different.