The producer will be at equilibrium at 3 units of output which satisfy both the conditions of producer's equilibrium.
(i) MC= MR
(ii) MC must be rising.

The producer achieves equilibrium at 6 units of output. At output levels 5th and 6th unit, the difference between TR and TC, i.e., profit is maximum, which is equal to 5 in both the cases. But the producer is in equilibrium at the 6th unit only where MR = MC (= 24) and MC is rising.

When there is no fixed price and price falls with the rise in output, MR curve slope downwards. Producer aims to produce that level of output. at which MC is equal to MRand MC curve cuts the MR curve from below. Let us understand this with the help of following table:

According to Table, both the conditions of equilibrium are satisfied at 4 units of output. MC is equal to MR and MC is rising. MC is more than MR when output is produced after 4 units of output. So, Producer's Equilibrium will be achieved at 4 units of output. Letus understand the determination of equilibrium with the help of a diagram:

Producer's Equilibrium is determined at OQ level of output corresponding to point E as at this point, MC= MR and MC curve cuts MR curve from below.
In Figure, output is shown on the horizontal axis and revenue and costs on the vertical axis. Producer's equilibrium will be determined at OQ level of output corresponding to point E because at this, the following two conditions are met:
(i) MC = MR; and
(ii) MCcurve cuts the MR curve from below.
When MR > MC, then producer will continue to produce as long as MR becomes equal to MC. It is so because firm will find it profitable to raise the output level.
When MR< MC, then producer will cut down the production as long as MR becomes equal to MC. It is so because firm will find it unprofitable to produce an extra unit. So, it starts reducing the level of output till MR= MC.
So, the producer is at equilibrium at OQ units of output.

When there is no fixed price and price falls with the rise in output, MR curve slope downwards. Producer aims to produce that level of output. at which MC is equal to MRand MC curve cuts the MR curve from below. Let us understand this with the help of following table:

According to Table, both the conditions of equilibrium are satisfied at 4 units of output. MC is equal to MR and MC is rising. MC is more than MR when output is produced after 4 units of output. So, Producer's Equilibrium will be achieved at 4 units of output. Letus understand the determination of equilibrium with the help of a diagram:

Producer's Equilibrium is determined at OQ level of output corresponding to point E as at this point, MC= MR and MC curve cuts MR curve from below.
In Figure, output is shown on the horizontal axis and revenue and costs on the vertical axis. Producer's equilibrium will be determined at OQ level of output corresponding to point E because at this, the following two conditions are met:
(i) MC = MR; and
(ii) MCcurve cuts the MR curve from below.
When MR > MC, then producer will continue to produce as long as MR becomes equal to MC. It is so because firm will find it profitable to raise the output level.
When MR< MC, then producer will cut down the production as long as MR becomes equal to MC. It is so because firm will find it unprofitable to produce an extra unit. So, it starts reducing the level of output till MR= MC.
So, the producer is at equilibrium at OQ units of output.

The producer achieves equilibrium at 6 units of output because at this point MC = MR and MC is rising. 

The profit-maximizing level of output is always determined where,
(i) MR = MC
(ii) MC must be rising. In other words, where price is equal to MC.
If price is not equal to MC, profit-maximizing condition cannot hold. It can be explained with the help of the following two cases:
Case 1: Price Greater Than MC
(i) In the given figure at output level q₂, the market price is greater than marginal cost.
(ii) To show that q₂ is not a profit maximizing level of output, we have taken q₃ output level, which is right of q₂.
(iii) Suppose the firm increases its output level from q₂ to q₃. The increase in total revenue of the firm from this output is the market price multiplied by the change in quantity (\(\triangle\) TR= market price x \(\triangle\)Q), that is, the area of rectangle q₂q₃CB.


(iv) On the other hand, the increase in total cost with this increase in output is the area of the region q₂q₃XW.
(v) But, a comparison of the two area shows that the firm's profit is higher when output level is q₂q₃ rather than %. So, % is not a profit maximizing level of output.
Case 2: Price Less Than MC
(i) In the given figure at output level q₂, the market price is less than marginal cost.
(ii) To show that %is not a profit maximizing level of output, we have taken q₃ output level, which is left of q₂.

(iii) Suppose now, that the firm reduce its output level from q₂ to q₃. The decrease in total revenue of the firm from this output is the market price multiplied by the change in quantity (\(\triangle\)TR = market price x \(\triangle\)Q), that is, the area of rectangle q₂q₃CB.
(iv) On the other hand, the decrease in total cost with this decrease in output is the area of the region q₂q₃WX.
(v) But, a comparison of the two area shows, that by reducing the output from q₂ to q₃, the decrease in cost is more than the loss in revenue.
So, q₂ is not a profit maximizing level of output.

The conditions must hold if a profit-maximizing firm produces positive output in a competitive market when price is constant under MR/MC approach is determined where,
(i) MR = MC (ii) MC must be rising

According to Table, both the conditions of equilibrium are satisfied at 4 units of output. MC is equal to MR and MC is rising. MC is more than MR when output is produced after 4 units of output. So, Producer's Equilibrium will be achieved at 4 units of output. However, MR is equal to MC at 2 units of output also. But, second condition is not fulfilled here.
Let us understand the determination of equilibrium with the help of a diagram:

Producer's Equilibrium is determined at OQ level of output corresponding to point E as at this point, MC= MR and MC curve cuts MR curve from below.
In Figure, output is shown on the horizontal axis and revenue and costs on the vertical axis. Producer's equilibrium will be determined at OQ level of output corresponding to point E because at this, the following two conditions are met:
(i) MC = MR;
(ii) MC curve cuts the MR curve from below.
When MR > MC, then producer will continue to produce as long as MR becomes equal to MC. It is so because firm will find it profitable to raise the output level.
When MR< MC, then producer will cut down the production as long as MR becomes equal to MC. It is so because firm will find it unprofitable to produce an extra unit. So, it starts reducing the level of output till MR= MC.

The conditions must hold if a profit-maximizing firm produces positive output in a competitive market when price is constant under MR/MC approach is determined where,
(i) MR = MC (ii) MC must be rising

According to Table, both the conditions of equilibrium are satisfied at 4 units of output. MC is equal to MR and MC is rising. MC is more than MR when output is produced after 4 units of output. So, Producer's Equilibrium will be achieved at 4 units of output. However, MR is equal to MC at 2 units of output also. But, second condition is not fulfilled here.
Let us understand the determination of equilibrium with the help of a diagram:

Producer's Equilibrium is determined at OQ level of output corresponding to point E as at this point, MC= MR and MC curve cuts MR curve from below.
In Figure, output is shown on the horizontal axis and revenue and costs on the vertical axis. Producer's equilibrium will be determined at OQ level of output corresponding to point E because at this, the following two conditions are met:
(i) MC = MR;
(ii) MC curve cuts the MR curve from below.
When MR > MC, then producer will continue to produce as long as MR becomes equal to MC. It is so because firm will find it profitable to raise the output level.
When MR< MC, then producer will cut down the production as long as MR becomes equal to MC. It is so because firm will find it unprofitable to produce an extra unit. So, it starts reducing the level of output till MR= MC.

The conditions must hold if a profit-maximizing firm produces positive output in a competitive market when price is constant under MR/MC approach is determined where,
(i) MR = MC (ii) MC must be rising

According to Table, both the conditions of equilibrium are satisfied at 4 units of output. MC is equal to MR and MC is rising. MC is more than MR when output is produced after 4 units of output. So, Producer's Equilibrium will be achieved at 4 units of output. However, MR is equal to MC at 2 units of output also. But, second condition is not fulfilled here.
Let us understand the determination of equilibrium with the help of a diagram:

Producer's Equilibrium is determined at OQ level of output corresponding to point E as at this point, MC= MR and MC curve cuts MR curve from below. 
In Figure, output is shown on the horizontal axis and revenue and costs on the vertical axis. Producer's equilibrium will be determined at OQ level of output corresponding to point E because at this, the following two conditions are met:
(i) MC = MR;
(ii) MC curve cuts the MR curve from below.
When MR > MC, then producer will continue to produce as long as MR becomes equal to MC. It is so because firm will find it profitable to raise the output level.
When MR< MC, then producer will cut down the production as long as MR becomes equal to MC. It is so because firm will find it unprofitable to produce an extra unit. So, it starts reducing the level of output till MR= MC.

The conditions must hold if a profit-maximizing firm produces positive output in a competitive market when price is constant under MR/MC approach is determined where,(i) MR = MC (ii) MC must be rising

According to Table, both the conditions of equilibrium are satisfied at 4 units of output. MC is equal to MR and MC is rising. MC is more than MR when output is produced after 4 units of output. So, Producer's Equilibrium will be achieved at 4 units of output. However, MR is equal to MC at 2 units of output also. But, second condition is not fulfilled here.
Let us understand the determination of equilibrium with the help of a diagram:

Producer's Equilibrium is determined at OQ level of output corresponding to point E as at this point, MC= MR and MC curve cuts MR curve from below.
 In Figure, output is shown on the horizontal axis and revenue and costs on the vertical axis. Producer's equilibrium will be determined at OQ level of output corresponding to point E because at this, the following two conditions are met:
(i) MC = MR;
(ii) MC curve cuts the MR curve from below.
When MR > MC, then producer will continue to produce as long as MR becomes equal to MC. It is so because firm will find it profitable to raise the output level.
When MR< MC, then producer will cut down the production as long as MR becomes equal to MC. It is so because firm will find it unprofitable to produce an extra unit. So, it starts reducing the level of output till MR= MC.