-15 π + 12 π

A landscape architect wished to enclose a rectangular garden on one side by a brick wall costing $20/ft and on the other three s

makvit [3.9K]

Answer:

The dimensions of the garden that minimize the cost is 9.018 feet(length) and 13.528 feet(width)

Step-by-step explanation:

Let the length of garden be x

Let the breadth of garden be y

Area of Rectangular garden = $Length \times Breadth = xy$

We are given that the area of the garden is 122 square feet

So, $xy=122$ ---A

A landscape architect wished to enclose a rectangular garden on one side by a brick wall costing $20/ft

So, cost of brick along length x = 20 x

On the other three sides by a metal fence costing $10/ft.

So, Other three side s = x+2y

So, cost of brick along the other three sides= 10(x+2y)

So, Total cost = 20x+10(x+2y)=20x+10x+20y=30x+20y

Total cost = 30x+20y

Substitute the value of y from A

Total cost = $30x+20(\frac{122}{x})$

Total cost = $\frac{2440}{x}+30x$

Now take the derivative to minimize the cost

$f(x)=\frac{2440}{x}+30x$

$f'(x)=-\frac{2440}{x^2}+30$

Equate it equal to 0

$0=-\frac{2440}{x^2}+30$

$\frac{2440}{x^2}=30$

$\sqrt{\frac{2440}{30}}=x$

$9.018 =x$

Now check whether it is minimum or not

take second derivative

$f'(x)=-\frac{2440}{x^2}+30$

$f''(x)=-(-2)\frac{2440}{x^3}$

Substitute the value of x

$f''(x)=-(-2)\frac{2440}{(9.018)^3}$

$f''(x)=6.6540$

Since it is positive ,So the x is minimum

Now find y

Substitute the value of x in A

$(9.018)y=122$

$y=\frac{122}{9.018}$

$y=13.528$

Hence the dimensions of the garden that minimize the cost is 9.018 feet(length) and 13.528 feet(width)

4 0

3 years ago

2. The actual tree on the left is 10 feet tall. The model tree on the right is 8 inches tall. What is the scale factor?

Lina20 [59]

Answer:

D. 1/15

Step-by-step explanation:

Actual tree = 10 ft = 12 × 10 = 120 in.

Model tree = 8 in.

Scale factor = model tree/actual tree

Scale factor = 8/120

Scale factor = 1/15

4 0

3 years ago

Simplify. 54+4(3/4−1/2)2

Effectus [21]

Answer:

56

Step-by-step explanation:

54 + 4(3/4 − 1/2)2

=> 54 + 4(1/4)2

=> 54 + (1)2

=> 54 + 2

=> 56

Therefore, 56 is our answer.

Hoped this helped.

7 0

3 years ago

Determine if the statement is true or false. If a linear system has the same number of equations and variables, then it must hav

lutik1710 [3]

Answer:

False

Step-by-step explanation:

Consider the equations with the same number of equations and variables as shown below,

Case 1

$x_{1} + x_{2} = 0\\x_{1} + x_{2} = 1$

This equation has no solution because it is not possible to have two numbers that give a sum of 0 and 1 simultaneously.

Case 2

$x_{1} + x_{2} = 1\\2x_{1} + 2x_{2} = 2$

This equation has infinitely many possible solutions.

Therefore it is FALSE to say a linear system with the same number of equations and variables, must have a unique solution.

5 0

3 years ago

What is 11/9/18 as a mixed number in simplest form.

12345 [234]

The answer is 22 because in order to divide fractions (in this case we would have 11 as a fraction), you need to multiply one fraction by the reciprocal of the other fraction (the flipped form of a fraction).

To find this, we would do $\frac{11}{1}$ * $\frac{9}{18}$ .

This would come to be $\frac{198}{9}$ , and when simplified by dividing the numerator and denominator by 9, you get 22.

4 0

4 years ago

-15 π + 12 π - 5 π =