Once a commercial plane reaches the desired altitude,

A school wishes to enclose its rectangular playground using 480 meters of fencing.

Harlamova29_29 [7]

Answer:

Part a) $A(x)=(-x^2+240x)\ m^2$

Part b) The side length x that give the maximum area is 120 meters

Part c) The maximum area is 14,400 square meters

Step-by-step explanation:

The picture of the question in the attached figure

Part a) Find a function that gives the area A(x) of the playground (in square meters) in terms of x

we know that

The perimeter of the rectangular playground is given by

$P=2(L+W)$

we have

$P=480\ m\\L=x\ m$

substitute

$480=2(x+W)$

solve for W

$240=x+W\\W=(240-x)\ m$

Find the area of the rectangular playground

The area is given by

$A=LW$

we have

$L=x\ m\\W=(240-x)\ m$

substitute

$A=x(240-x)\\A=-x^2+240x$

Convert to function notation

$A(x)=(-x^2+240x)\ m^2$

Part b) What side length x gives the maximum area that the playground can have?

we have

$A(x)=-x^2+240x$

This function represent a vertical parabola open downward (the leading coefficient is negative)

The vertex represent a maximum

The x-coordinate of the vertex represent the length that give the maximum area that the playground can have

Convert the quadratic equation into vertex form

$A(x)=-x^2+240x$

Factor -1

$A(x)=-(x^2-240x)$

Complete the square

$A(x)=-(x^2-240x+120^2)+120^2$

$A(x)=-(x^2-240x+14,400)+14,400$

$A(x)=-(x-120)^2+14,400$

The vertex is the point (120,14,400)

therefore

The side length x that give the maximum area is 120 meters

Part c) What is the maximum area that the playground can have?

we know that

The y-coordinate of the vertex represent the maximum area

The vertex is the point (120,14,400) -----> see part b)

therefore

The maximum area is 14,400 square meters

Verify

$x=120\ m$

$W=(240-120)=120\ m$

The playground is a square

$A=120^2=14,400\ m^2$

8 0

3 years ago

If, for all x, f'(x)=(x-2)^4(x-1)^3, it follows that funtaion f has

Elenna [48]

Answer:

We say that f(x) has an absolute (or global) minimum at x=c if f(x)≥f(c) f ( x ) ≥ f ( c ) for every x in the domain we are working on. We say that f(x) has a relative (or local) minimum at x=c iff(x)≥f(c) f ( x ) ≥ f ( c ) for every x in some open interval around x=c .

4 0

3 years ago

4. 46 is what percent of 69?

sergij07 [2.7K]

Answer:

66%(technically 0.66 repeating)

Step-by-step explanation:

We need to figure out what percentage of 69 equates to 46. In other words, we need to figure out what percentage times 69 equals 46:

$percentage*69 = 46$

Now that we formed this equation, we can solve for the percentage as if it was x.

First lets simplfy:

$percentage*69 = 46 -- > 69percentage = 46$

Now we can solve for x just by getting x alone, which means we must remove the coefficent. We can do this by dividing both sides of the equation by 69:

$percentage = \frac{46}{69}$

=

$percentage=0.66$

Putting this into the form of percentage, we must multiply by 100. Since, the percentage form of a decimal is 100 times bigger(moved up 2 decimal places):

$percentage = 0.66*100$