A= x^2 -30x+225 The polynomial represents the area (in square feet) of the square playground. a. Write a polynomial that represents the side length of the playground. b. Write an expression for the perimeter of the playground. (I factored it and got (x-15)^2)

Respuesta :

Answer:

a) The polynomial is equivalent to [tex]A = (x-15)^{2}[/tex], and the side length of the playground is [tex]x -15[/tex] feet.

b) The perimeter of the playground, measured in feet, is [tex]p = 4\cdot (x-15)[/tex].

Step-by-step explanation:

a) By Geometry, we know that area of the square is equal to the square of the side length. If [tex]A = x^{2}-30\cdot x +225[/tex] is the area of the square, then must be a perfect square trinomial, that is:

[tex](x-a)^{2} = x^{2}-2\cdot a\cdot x + a^{2}[/tex] (1)

Then, we must observe the following properties:

[tex]-2\cdot a = -30[/tex] (2)

[tex]a = 15[/tex]

[tex]a^{2} = 225[/tex] (3)

[tex]a = 15[/tex]

Therefore, the polynomial is equivalent to [tex]A = (x-15)^{2}[/tex], and the side length of the playground is [tex]x -15[/tex] feet.

b) The perimeter of a square equals four times the side length. That is:

[tex]p = 4\cdot (x-15)[/tex]

The perimeter of the playground, measured in feet, is [tex]p = 4\cdot (x-15)[/tex].

The polynomial that represents the side length is x - 15, and the perimeter of the playground is 4x - 60

The expression of the area is given as:

[tex]A = x^2 - 30x + 225[/tex]

Expand the expression

[tex]A = x^2 - 15x - 15x + 225\\[/tex]

Factorize

[tex]A= (x - 15)^2[/tex]

The area of a square is:

[tex]A = l^2[/tex]

Where l represents the side length.

So, we have:

[tex]l = x - 15[/tex]

The perimeter is then calculated as:

[tex]P = 4l = 4*( x - 15)[/tex]

[tex]P = 4x - 60[/tex]

Hence, the perimeter of the playground is 4x - 60

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