Arectangular plot of farmland will be bounded on one side by a river and on the other three sides by a single-strand electric fence. with 1000 m of wire at your disposal, what is the largest area you can enclose, and what are its dimensions?

The largest area is 125000 m²

The dimensions of the farmland are 250 m and 500 m

Step-by-step explanation:

* Lets pick the information from the problem

- The farmland is shaped a rectangle

- The farmland will be bounded on one side by a river

- The other three sides are bounded by a single-strand electric fence

- The length of wire is 1000 m

- Lets consider the width of the rectangle is x and the length is y

- The side which will be bounded by the river is y

∴ The perimeter of the farmland which will be bounded by the electric

  fence = x + x + y  = 2x + y

- We will use the wire to fence the farmland

∵ The length of the wire is 1000 m

∵ The perimeter of the farmland is equal to the length of the wire

∴ 2x + y = 1000

- Lets find y in term of x

∵ 2x + y = 1000 ⇒ subtract 2x from both sides

∴ y = 1000 - 2x

- Now lets find the area can enclose by the wire

∵ The area of the rectangle = length × width

∵ The width of the farmland is x and its length is y

∴ The area of the farmland (A) = x × y = xy ⇒ (2)

- Use equation (1) to substitute the value of y in equation (2)

∴ A = x (1000 - 2x) ⇒ simplify

∴ A = 1000 x - 2 x²

- To find the maximum area we will differentiate A with respect to x

  and equate the answer by zero to find the value of x which will make

  the enclosed area largest

* Lets revise the rule of differentiation

- If y = ax^n, then dy/dx = a(n) x^(n-1)

- If y = ax, then dy/dx = a

- If y = a, then dy/dx = 0 , where a is a constant

∵ A = 1000 x - 2 x² ⇒ (3)

- Differentiate A with respect to x using the rules above

∴ dA/dx = 1000 - 2(2) x^(2-1)

∴ dA/dx = 1000 - 4x

- Put dA/dx = 0 to find the value of x

∵ 1000 - 4x = 0 ⇒ add 4x to both sides

∴ 1000 = 4x ⇒ divide both sides by 4

∴ 250 = x

∴ The value of x is 250

- Lets substitute this value in equation 3 to find the largest area

∵ A = 1000 x - 2 x²

∴ A = 1000 (250) - 2(250)² = 125000 m²

* The largest area is 125000 m²

∵ The width of the farmland is x

∵ x = 250

∴ The width of the farmland = 250 m

- Substitute the value of x in the equation (1) to find y

∵ y = 1000 - 2x

∵ x = 250

∴ y = 1000 - 2(250) = 1000 - 500 = 500

∵ The length of the farm lend is y

∴ The length of the farm land = 500 m

* The dimensions of the farmland are 250 m and 500 m

answer: the value should be used for i in the formula of calculation the monthly payment , the interest rate per period is 0.85.

step-by-step explanation:

the given rate of interest i= 85%

in calculating the monthly payment for a loan with an interest rate compounded monthly, the value of the interest rate per period we use in the formula must be in decimal form.

to convert it in decimal, we divide it by 100, we get

hence, the value should be used for i in the formula of calculation the monthly payment , the interest rate per period is 0.85.