Two points of y=x2-4x+7

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

MP3 payer: $150; 22% markup

bearhunter [10]

183 is the price after the markup

7 0

3 years ago

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Describe the total change to Ms. Thomas' savings account balance after making six monthly payments on her car loan. Model your a

Butoxors [25]

Answer:

$-1465.5

Step-by-step explanation:

Complete question

Every month, Ms. Thomas pays her car loan through automatic payments (withdrawals) from her savings account. She pays the same amount on her car loan each month. At the end of the year, her savings account balance changed by −$2,931 from payments made on her car loan. Describe the total change to Ms. Thomas’ savings account balance after making six monthly payments on her car loan. Model your answer using a number sentence.

Given the following

Savings balance (after 1 year) =

−$2,931

If she pays the same amount on her car loan each month, we are to find the total change to Ms. Thomas’ savings account balance after making six monthly payments on her car loan, this can be expressed as;

$x = 6months savings

Solving both equalities

Savings balance (after 1 year) =

−$2,931

Since 1year = 12months

-$2,931 =12months savings

$x = 6months savings

To get the total savings after 6months we will find x by cross multiplying;

12×x = -2931×6

Divide through by 12

12x/12 = (-2931×6)/12

x = -2931/2

x = -1465.5

Hence Ms. Thomas' savings account balance after making six monthly payments on her car loan is $-1465.5

7 0

3 years ago

WILL GIVE BRAINIEST TO THE PERSON THAT ANSWERS ALL THREE QUESTIONS ASAP!

Radda [10]

Answer:

1. Your answer would be C) 2√3-5√2.

2. Your answer would be -39.7i.

3. Your answer would be -1.

Step-by-step explanation:

8 0

3 years ago

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Three years hence a father will four times as old as his son will be. Before two years he was seven times as old as his son was.

myrzilka [38]

Answer: The father is 37 years and the son is 7 years

Step-by-step explanation:

Let x represent the present age of the father.

Let y represent the present age of the son.

Three years hence a father will four times as old as his son will be. This means that

x + 3 = 4(y + 3)

x + 3 = 4y + 12

x - 4y = 12 - 3

x - 4y = 9- - - - - - - - - - - - - - - -1

Before two years he was seven times as old as his son was. This means that

(x - 2) = 7(y - 2)

x - 2 = 7y - 14

x - 7y = - 14 + 2

x - 7y = - 12- - - - - - - - - - - - - - -2

Subtracting equation 2 from equation 1, it becomes

3y = 21

y = 21.3 = 7

Substituting y = 7 into equation 1, it becomes

x - 4 × 7 = 9

x - 28 = 9

x = 9 + 28

x = 37

7 0

3 years ago

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