6. Consider the following Total Revenue (TR) and Total Cost (TC) functions for a firm operating in a perfect competition market:

[tex]\[
TR = 6Q \quad \text{and} \quad TC = Q^3 - 2Q^2 + 50Q + 25
\][/tex]

A. Determine the profit-maximizing or loss-minimizing equilibrium level of output.

B. Compute the level of profit or loss at the above equilibrium quantity and comment on the decision of the firm.

C. Mathematically and graphically derive the supply function of the firm.



Answer :

Certainly! Let's tackle each part of the question separately.

### Part A: Determine the Profit Maximizing or Loss Minimizing Equilibrium Level of Output

1. Profit Function: The profit, [tex]\( \pi \)[/tex], is given by the difference between Total Revenue (TR) and Total Cost (TC):
[tex]\[ \pi(Q) = TR(Q) - TC(Q) = 6Q - (Q^3 - 2Q^2 + 50Q + 25) \][/tex]
Simplifying the profit function:
[tex]\[ \pi(Q) = 6Q - Q^3 + 2Q^2 - 50Q - 25 \][/tex]
[tex]\[ \pi(Q) = -Q^3 + 2Q^2 - 44Q - 25 \][/tex]

2. Finding Critical Points: To find the equilibrium quantity, we need to determine the critical points by setting the first derivative of the profit function equal to zero.
[tex]\[ \frac{d\pi}{dQ} = \frac{d}{dQ} (-Q^3 + 2Q^2 - 44Q - 25) \][/tex]
Calculating the derivative:
[tex]\[ \frac{d\pi}{dQ} = -3Q^2 + 4Q - 44 \][/tex]
Setting the first derivative equal to zero to find the equilibrium quantity:
[tex]\[ -3Q^2 + 4Q - 44 = 0 \][/tex]

3. Solving the Quadratic Equation:
[tex]\[ -3Q^2 + 4Q - 44 = 0 \][/tex]
Use the quadratic formula [tex]\( Q = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \)[/tex] where [tex]\( a = -3 \)[/tex], [tex]\( b = 4 \)[/tex], and [tex]\( c = -44 \)[/tex]:
[tex]\[ Q = \frac{-4 \pm \sqrt{4^2 - 4(-3)(-44)}}{2(-3)} \][/tex]
[tex]\[ Q = \frac{-4 \pm \sqrt{16 - 528}}{-6} \][/tex]
Since the discriminant [tex]\( (16 - 528 = -512) \)[/tex] is negative, the quadratic equation has no real roots.

4. Conclusion for Part A:
Since the quadratic has no real roots, the profit function does not have a maximum or minimum within the real domain. Thus, there is no profit-maximizing or loss-minimizing equilibrium output that we can solve for using real numbers. This likely indicates external factors or constraints around real-world production levels.

### Part B: Compute the Level of Profit or Loss at the Above Equilibrium Quantity and Comment

Since we found no real equilibrium point (no real [tex]\( Q \)[/tex] roots from the quadratic equation), we cannot calculate a specific profit or loss at an equilibrium level mathematically derived from the given functions.

However, to proceed practically, it would involve looking into potential boundary conditions or values in a feasible range for [tex]\( Q \)[/tex].

### Part C: Derive the Supply Function of the Firm

1. Marginal Cost (MC) Function: The supply function in a perfectly competitive market is the marginal cost (MC) curve above the average variable cost (AVC):
[tex]\[ TC(Q) = Q^3 - 2Q^2 + 50Q + 25 \][/tex]
The MC is the first derivative of the TC function:
[tex]\[ MC = \frac{d(TC)}{dQ} = \frac{d}{dQ} (Q^3 - 2Q^2 + 50Q + 25) \][/tex]
Calculating the derivative:
[tex]\[ MC = 3Q^2 - 4Q + 50 \][/tex]

2. Supply Function: In a perfectly competitive market, firms produce where [tex]\( P = MC \)[/tex]. Given that [tex]\( P = 6 \)[/tex]:
[tex]\[ 6 = 3Q^2 - 4Q + 50 \][/tex]
Solving for [tex]\( Q \)[/tex]:
[tex]\[ 3Q^2 - 4Q + 44 = 0 \][/tex]
This quadratic equation has the same coefficients, leading to the recognition that the discriminant is the same: negative.

3. Conclusion for Part C:
Since again the discriminant is negative, implying no real [tex]\( Q \)[/tex] solution, it reflects more real-world constraints on firm production levels. Thus, there may be other factors or conditions impacting the firm's ability to supply.

### Summary
- Part A: No real equilibrium quantity found mathematically.
- Part B: Unable to compute specific profit or loss at equilibrium points that don't exist in real domain of [tex]\( Q \)[/tex].
- Part C: Supply function derivation also results in no real solutions for [tex]\( Q \)[/tex] upon solving [tex]\( MC = P \)[/tex].

The findings indicate practical constraints, misalignments, or further considerations needed beyond the given equations to form a comprehensive real-world model.