# Algebra help

• Sep 5th 2009, 07:48 PM
Bobalina
Algebra help
Hi, I'm having trouble with this question.

Find the minimum for y
y=(a+x)(b+x)\cx
c,x,b,a>0

Can anyone help? Thanks.
• Sep 5th 2009, 08:02 PM
sammylemon
Hi
To solve this problem lets first expand through

solve for dervitive
set y prime =0
solve for x

put x into y equations
and proove one of smaller thne the other
• Sep 5th 2009, 08:04 PM
Bobalina
Sorry, what is 'lim'? Limit?
• Sep 5th 2009, 08:04 PM
sammylemon
yes
• Sep 5th 2009, 08:07 PM
Bobalina
Thanks so far, although I still don't understand this part:

now you said a,b,c,x >0 so if we take a lim x-> 0

limx->0 ab/cx + b/c +a/c + x/c
• Sep 5th 2009, 08:13 PM
sammylemon
oh nvm im very wroung

hehe sorry

take the derivtive solve for x at y prime=0
you should get 2 values
find the lower value by pulling both into original y equations lower one is ur result

in this cause ull have to prove on os smaller then the other
• Sep 5th 2009, 08:25 PM
Bobalina
Sorry, I don't really understand? :S