f(x)=-2x^2+400x is the function of a rectangular area, how can I find the largest area possible?

Question

loser66 · Answer

do you know derivative?

lucaz · Answer

without calculus, I think I need the vertex?

loser66 · Answer

oh, we still have way to find out vertex, yes!! you are right

loser66 · Answer

so? what is the vertex?

lucaz · Answer

hmm

jdoe0001 · Answer

$\bf f(x)=-2x^2+400x\implies f(x)=-2x^2+400x+0\ \quad \ \quad \
f(x)=ax^2+bx+c\qquad \textit{vertex will be at }\left(-\cfrac{b}{2a}\quad ,\quad  c-\cfrac{b^2}{4a}\right)$

lucaz · Answer

right, thanks

loser66 · Answer

@lucaz I read your nick and realize that it is pronounced like "loca" by shakira. I forgot the name of the song until saw your nick, hihihi., enjoy http://www.youtube.com/watch?v=76VY054ghpk

lucaz · Answer

what a nice thing to know about my nick ¬¬