Example
Alice's utility for chocolate and strawberries is
$$u \left( X, Y \right) = X^2 \times Y$$Her marginal utility for chocolate is
$$ \begin{equation*} MU_X = \frac{du \left( X, Y \right)}{dX} = \frac{d X^2 Y}{dX} = 2 X Y \end{equation*} $$Her marginal utility for strawberries is
$$ \begin{equation*} MU_Y = \frac{du \left( X, Y \right)}{dY} = \frac{d X^2 Y}{dY} = X^2 \end{equation*} $$Question
Now Alice's utility is `u (X, Y) = X^{493} Y^{105}`. Compute her marginal utility for strawberries?
Her marginal utility for strawberries is the derivative of `u (X, Y) = X^{493} Y^{105}` with regards to `Y`.
$$ \begin{align*} MU_Y = \frac{du(X, Y)}{dY} = 105 X^{493} Y^{105 - 1} = 105 X^{493} Y^{104} \end{align*} $$