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Calculus help (Optimization Integration)
Ipquarx:
--- Quote from: Pastrey Crust on February 13, 2017, 09:01:07 PM ---I started off with
w*3w*(4w-60)=0
--- End quote ---
If anything it would simplify to minimizing 3w^2*(60-4w), not 3w^2*(4w-60). I think that's why you got a negative number.
l+w+h=60
h=60-l-w
h=60-4w
Pastrey Crust:
ah yes
silly me
I feel stupid for screwing up in silly things.
Texan101:
--- Quote from: Pastrey Crust on February 13, 2017, 09:01:07 PM ---Yes, that.
Rectangular prism. L = 3w L+W+H = 60
I got a negative answer for some reason. I started off with
w*3w*(4w-60)=0
--- End quote ---
With the equation w*3w*(4w-60), we can simplify to easily find w. 3w^2 * (4w-60) is equivalent, and gives us three answers. Either 3w^2 = 0 (The first two of our answers, since this could normally be positive or negative), or 4w = 60, which comes to w = 15.
I highly doubt this was your mistake.
Ipquarx:
--- Quote from: Texan101 on February 13, 2017, 10:07:48 PM ---
With the equation w*3w*(4w-60), we can simplify to easily find w. 3w^2 * (4w-60) is equivalent, and gives us three answers. Either 3w^2 = 0 (The first two of our answers, since this could normally be positive or negative), or 4w = 60, which comes to w = 15.
I highly doubt this was your mistake.
--- End quote ---
No, we're trying to maximize 3w2(60-4w), not make it 0.
Texan101:
--- Quote from: Ipquarx on February 13, 2017, 10:14:47 PM ---No, we're trying to maximize 3w2(4w-60), not make it 0.
--- End quote ---
Alright, that's a better challenge.
So, distributing 3w^2 yeilds 12w^3-60w^2
The derivative, in relation to w, is 36w^2-120w
There is no maximum to this equation. Only a minimum.