Remark
I didn't know this was a calculus question. How dumb of me.
f(x + h) - f(x)
==========
x + h - h
50/6 - 51/6 =( -1/6+ h)/h
The h's will disappear when the limit is taken.
answer - 1/6 which is A. If anyone else answers take their answer.
Answer:
<em>The least number of items to produce is 41</em>
Step-by-step explanation:
<u>Average Cost</u>
Given C(x) as the cost function to produce x items. The average cost is:

The cost function is:

And the average cost function is:

We are required to find the least number of items that can be produced so the average cost is less or equal to $21.
We set the inequality:

Multiplying by x:

Note we multiplied by x and did not flip the inequality sign because its value cannot be negative.
Adding 20x:


Swapping sides and changing the sign:

Dividing by 41:

The least number of items to produce is 41
Distribute on both sides
2x - 8 = 6x + 12
Move x to one side
-20 = 4x
Divide by 4
-5 = x
The sum its +2
2+2=4
4+2=6
6+2=8
8+2=10
And so on the numbers just keep sum for 2