- #1
rohanprabhu
- 414
- 2
[SOLVED] Maximum value of xy
Q] Given that [itex]x \in [1, 2][/itex] and [itex]y \in [-1, 1][/itex] and [itex]x + y = 0[/itex], find the maximum value of [itex]xy[/itex]
I have no idea at all. Does this have something to do with the maxima/minima. In that case, i can get that:
[tex]
\frac{dx}{dy} = xdy + ydx
[/tex]
also,
[tex]
dx = -dy
[/tex]
hence, for the condition of [itex]f'(x) = 0[/itex],
[tex]
xdy + ydx = 0
[/tex]
[tex]
xdy = - ydx
[/tex]
[tex]
\frac{dy}{dx} = \frac{-y}{x}
[/tex]
i don't even know what I'm doing till now.
Homework Statement
Q] Given that [itex]x \in [1, 2][/itex] and [itex]y \in [-1, 1][/itex] and [itex]x + y = 0[/itex], find the maximum value of [itex]xy[/itex]
The Attempt at a Solution
I have no idea at all. Does this have something to do with the maxima/minima. In that case, i can get that:
[tex]
\frac{dx}{dy} = xdy + ydx
[/tex]
also,
[tex]
dx = -dy
[/tex]
hence, for the condition of [itex]f'(x) = 0[/itex],
[tex]
xdy + ydx = 0
[/tex]
[tex]
xdy = - ydx
[/tex]
[tex]
\frac{dy}{dx} = \frac{-y}{x}
[/tex]
i don't even know what I'm doing till now.