If the demand equation for a particular commodity is y=28-5x, where y is the unit price in pesos and x is the quantity in units, find the total revenue function and marginal revenue function.

R(x) = Px

R(x) = (28-5x)x
R(x) = 28x - 5x^2

To find the total revenue function and marginal revenue function, we need to understand the formulas for these concepts.

Total revenue (TR) is the product of the unit price (y) and the quantity (x) of the commodity sold. Mathematically, TR = y * x.

Marginal revenue (MR) is the additional revenue earned from selling one more unit of the commodity. It is calculated by finding the derivative of the total revenue function with respect to the quantity (x). Symbolically, MR = d(TR)/dx.

Now, let's find the total revenue function and marginal revenue function using the given demand equation, y = 28 - 5x.

Total Revenue Function (TR):
Substitute the given demand equation y = 28 - 5x into the total revenue formula TR = y * x:

TR = (28 - 5x) * x
= 28x - 5x^2

Hence, the total revenue function is TR = 28x - 5x^2.

Marginal Revenue Function (MR):
To find the marginal revenue function, take the derivative of the total revenue function (TR) with respect to x:

MR = d(TR)/dx
= d(28x - 5x^2)/dx
= 28 - 10x

Therefore, the marginal revenue function is MR = 28 - 10x.

In summary:
Total Revenue Function: TR = 28x - 5x^2
Marginal Revenue Function: MR = 28 - 10x