Knore88
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A consumer spends a positive amount (m) in order to buy (x) units of one good at the price of 6 per unit, and (y) units of a different good at the price of 10 per unit. The consumer chooses (x) and (y) to maximize the utility function
U(x, y) = (x + y)(y + 2).
I need to find the optimal quantities x* and y*, as well as the Lagrange multiplier, all as functions of m.
FOC:
$${L}_{x}$$ = y + 2 - 6$$\lambda$$ = 0 (i)
$${L}_{y}$$ = x + 2y + 2 - 10$$\lambda$$ = 0 (ii)
6x + 10y - m = 0 (iii)
From (i): $$\lambda$$ = $$\frac{y + 2}{6}$$
From (ii): $$\lambda$$ = $$\frac{x + 2y + 2}{10}$$
$$\therefore$$
x*(m) = $$\frac{5}{3}$$ - $$\frac{m}{24}$$
y*(m) = $$\frac{m}{8}$$ - 1
$$\lambda$$*(m) = $$\frac{m}{48}$$ + $$\frac{1}{6}$$
Next I need to find the maximum utility value as a function of m.
I plugged the values for x* and y* into the utility function and obtained
U(m or m*?) = $$\frac{m(m + 16)}{96}$$ + $$\frac{2}{3}$$ ?
Finally, I need to find for what values of m this solution is valid. I'm not quite sure how to do this part?
U(x, y) = (x + y)(y + 2).
I need to find the optimal quantities x* and y*, as well as the Lagrange multiplier, all as functions of m.
FOC:
$${L}_{x}$$ = y + 2 - 6$$\lambda$$ = 0 (i)
$${L}_{y}$$ = x + 2y + 2 - 10$$\lambda$$ = 0 (ii)
6x + 10y - m = 0 (iii)
From (i): $$\lambda$$ = $$\frac{y + 2}{6}$$
From (ii): $$\lambda$$ = $$\frac{x + 2y + 2}{10}$$
$$\therefore$$
x*(m) = $$\frac{5}{3}$$ - $$\frac{m}{24}$$
y*(m) = $$\frac{m}{8}$$ - 1
$$\lambda$$*(m) = $$\frac{m}{48}$$ + $$\frac{1}{6}$$
Next I need to find the maximum utility value as a function of m.
I plugged the values for x* and y* into the utility function and obtained
U(m or m*?) = $$\frac{m(m + 16)}{96}$$ + $$\frac{2}{3}$$ ?
Finally, I need to find for what values of m this solution is valid. I'm not quite sure how to do this part?