You have 50 ft of fencing and want to fence in a rectangular area of 144 ft^2. What are going to
be the dimensions of the rectangular area?
Quadratic equation

Respuesta :

Answer:

16 by 9 feet.

Step-by-step explanation:

We have 50 feet of fencing in total.

Therefore, the perimeter of our area is 50. Perimeter is given by:

[tex]P=2(\ell+w)[/tex]

Substituting 50 for P yields:

[tex]50=2(\ell+w)[/tex]

And dividing both sides by 2 yields:

[tex]\ell+w=25[/tex]

The area of a rectangular is given by:

[tex]A=\ell w[/tex]

Where [tex]\ell[/tex] is the length and [tex]w[/tex] is the width.

We want to enclose 144 feet squared. So, A=144:

[tex]144=\ell w[/tex]

By the perimeter equation, we can subtract a variable, say [tex]\ell[/tex] from both sides. Hence:

[tex]w=25-\ell[/tex]

Now, we can substitute this into our area equation. Therefore:

[tex]144=\ell(25-\ell)[/tex]

Distribute:

[tex]144=25\ell-\ell^2[/tex]

Subtract 144 from both sides:

[tex]-\ell^2+25\ell-144=0[/tex]

Divide everything by -1:

[tex]\ell^2-25\ell +144=0[/tex]

Factor:

[tex](\ell-9)(\ell-16)=0[/tex]

Zero Product Property:

[tex]\ell_1=9\text{ or } \ell_2=16[/tex]

Then it follows that:

[tex]w_1=25-(\ell_1)=25-9=16[/tex]

Or:

[tex]w_2=25-(\ell_2)=25-(16)=9[/tex]

Regardless, the dimensions of the rectangular area will be 16 by 9 feet.

Answer:

p = 2(l +w)

l= p÷2 -w = l= 25 -w

A= l x w =( 25 -W)W= 144

-w^2 +25w-144 =0

-w^2 +9w+16w- 144=0

(-w^2+9w) +(16w- 144) =0

-w(w - 9) + 16(w - 9) =0

(-w +16) = 0 or w - 9 =0

w = 9 or w = 16

so l = 25 - 9 = 16

or l = 25 - 16 = 9

therefore l = 16ft and w= 9ft