Slightly advanced math

[SeeDRankLou]

I was in my linear algebra class, and I was taking notes about how to prove Holder's Inequality. There is this one part (noted in red), I don't know how I went from 1 to 2.

http://i47.photobucket.com/albums/f155/maddylouis/EoFF/whatdidido.jpg

How did I (or my professor) go from 1 to 2?

[FFIX Choco Boy]

Remember Factoring polynomials? Same thing.

3x^2+7x+2=0
(3x^2+6x)+(x+2)=0

Then take out the GCF.
3x(x+2)+(x+2)=0

Reduce.
3x(x+2)=0

3x=0 x+2=0

x=0 x=-2

{-2, 0}

[Tavrobel]

Remember Factoring polynomials? Same thing.

LOL no. First off, you factored your own example incorrectly.

3x² + 7x + 2 = 0 becomes
(3x+1)(x+2) = 0
x = -1/3 and -2

So that was just plain wrong. Also, I believe you have a severe misconception about what Linear Algebra is. It's Calculus level math, and SRL is working with matrices anyways (at least, that what it appears to be like). I have no idea how he got that 2 coefficient, but try working out the matrices that are given. Maybe a negative somewhere didn't cancel out? When SRL said "slightly," he may have sort of meant "very." It's a joke.

[Aerith's Knight]

I think he used Young's inequality (http://en.wikipedia.org/wiki/Young%27s_inequality) to do that step.

It seems to follow that pattern, although I don't have the time to check it myself, sorry.

Good luck with the subject. I only scraped by with a 70% on Lineair Algebra myself. ^_^'

[FFIX Choco Boy]

LOL no. First off, you factored your own example incorrectly.

3x² + 7x + 2 = 0 becomes
(3x+1)(x+2) = 0
x = -1/3 and -2

My mistake, wasn't paying much attention. But, yes, it seems to be the same basic process. I may be misreading some of his notes, because I don't pay a whole lot of attention anyways, but it seems at least very similar.

Hmm, just looked at it again, yup I looked at it wrong. Disregard and forget.

[I Don't Need A Name]

why does american 'math' look so different to english maths?

[Aerith's Knight]

Looks the same as my dutch lineair Algebra, so I think it's just you. :p

[SeeDRankLou]

Yeah, it's Young's Inequality. My professor mentioned this in the next class, and then I found where I put this in my notes, it just wasn't given a name. Thanks everyone.