Who is sigma Lazyeight?

A fence is to be built to enclose a rectangular area of 450 square feet. The fence along three sides is to be made of material t

Mila [183]

Answer:

The short side is _15___ft and the long side is ___30___ ft.

Step-by-step explanation:

As fence is built in a rectangular area, so we can consider

Let

x be the length of the rectangle

y be width of the rectangle

Given area of rectangle is = 450 ft²

Formula for area of rectangle = Length x width

450 ft² = xy

Solve for y

y = 450/x

now according to given condition

three sides of the fence costs $5 per foot and for the fourth side costs$15 per foot.

We have two condition either the fourth side be x or y

So condition 1: Three sides =(x,y,x) 4-th side = y.

So we can write as 5x,5y,5x and 15 y

Cost C = 5x +5y+5x+15y

= 10x+ 5y+15y

= 5(2x+y) +15y----------------equation 1

= 10x +20y

Adding value of y 450/x

= 10x + 20(450/x)

= 10x + 9000/x

For minimum cost, we can consider the cost to be 0

0 = 10x + 9000/x

Dividing and multiplying by -x/x

0 = -10 +9000/x²

10 = 9000/x²

10x² = 9000/

x²= 900

x = 30

so y = 450/x = 450/30= 15 ft

so adding the values of x and y in equation 1 we will have

cost C= 5(2x+y) +15y----------------equation 1

cost is = 5(2(30)+15) +15(15)

= $600 is the cost

X= 30 y =15

So condition 2: Three sides =(y,x,y) 4-th side = x.

So we can write as 5y,5x,5y and 15 x

Cost C = 5y +5x+5y+15x

= 5x+ 10y+15x

= 5(x+2y) +15x----------------equation 2

= 20x +10y

Adding value of y= 450/x

= 20x + 10(450/x)

= 20x + 4500/x

For minimum cost, we can consider the cost to be 0

0 = 20x + 4500/x

Dividing and multiplying by -x/x

0 = -20 +4500/x²

20 = 4500/x²

20x² = 4500

x²= 4500/20= 225

x = 15

so y = 450/x = 450/15= 30 ft

so adding the values of x and y in equation 2 we will have

cost C= = 5(x+2y) +15x----------------equation 2

cost is = 5(15+2(30) +15(15)

= $600 is the cost

y= 30 x=15

so from both conditions satisfy the cost and the two sides are known as length and width

so dimension will be 15 ft by 30 ft

7 0

2 years ago

Help please don’t understand.

sergij07 [2.7K]

Okay so first, area is length times width, so 1/4x*x would be first = 1/4(x^2)=64. Then area or x = 16 or -16

perimeter would be width times two plus length times two. I recommend using math papa to calculate these numbers.

4 0

2 years ago

In 2 + In 8 - In 4 In 4 In 6 In 64 DONE

Alex

Answer:

ln 4

Step-by-step explanation:

plus(+) will become times and minus(-)will become divide. Combine all together as all are in terms of ln

ln (2x8)/4

=ln 4

7 0

2 years ago

Need help with Calculus 1 inverse trig functions

lidiya [134]

Answer:

$\displaystyle y'=3\frac{1+\frac{x}{\sqrt{1+x^2}}}{2+2x^2+2x\sqrt{1+x^2}}$

Step-by-step explanation:

The Derivative of a Function

The derivative of f, also known as the instantaneous rate of change, or the slope of the tangent line to the graph of f, can be computed by the definition formula

$\displaystyle f'(x)=\lim\limits_{\Delta x \rightarrow 0}\frac{f(x+\Delta x)-f(x)}{\Delta x}$

There are tables where the derivative of all known functions are provided for an easy calculation of specific functions.

The derivative of the inverse tangent is given as

$\displaystyle (tan^{-1}u)'=\frac{u'}{1+u^2}$

Where u is a function of x as provided:

$y=3tan^{-1}(x+\sqrt{1+x^2})$

If we set

$u=(x+\sqrt{1+x^2})$

Then

$\displaystyle u'=1+\frac{2x}{2\sqrt{1+x^2}}$

$\displaystyle u'=1+\frac{x}{\sqrt{1+x^2}}$

Taking the derivative of y

$y'=3[tan^{-1}(x+\sqrt{1+x^2})]'$

Using the change of variables

$\displaystyle y'=3[tan^{-1}u]'=3\frac{u'}{1+u^2}$

$\displaystyle y'=3\frac{u'}{1+u^2}=3\frac{1+\frac{x}{\sqrt{1+x^2}}}{1+(x+\sqrt{1+x^2})^2}$

Operating

$\displaystyle y'=3\frac{1+\frac{x}{\sqrt{1+x^2}}}{1+x^2+2x\sqrt{1+x^2}+1+x^2}$

$\boxed{\displaystyle y'=3\frac{1+\frac{x}{\sqrt{1+x^2}}}{2+2x^2+2x\sqrt{1+x^2}}}$

8 0

2 years ago

Help please ..........

olganol [36]

Answer:

7. combination; 25C6 = 177100

8. combination; 15C5 = 3003

Step-by-step explanation:

7. The order of the committee member selections is not important. (It would be if specific people filled specific positions on the committee.) Hence, the number is a number of combinations of 25 people taken 6 at a time.

__

8. The order of players is not important, as it might be if specific choices filled specific positions on the team. (The problem statement gives no indication that is the case. It is only by our knowledge of basketball teams that we entertain the possibility that order might be important.) Hence, the number is a number of combinations of 15 people taken 5 at a time.

_____

Of course, nCk = n!/(k!(n-k)!)

7 0

3 years ago