Stacey has a square piece of cloth. She cuts 3 inches off of the length of the square and 3 inches off of the width. The area of the smaller square is 1/4the area of the original square. What was the side length of the original square?

Respuesta :

Answer:

The side length of the original square was 6 inches

Step-by-step explanation:

we know that

The area of a square is

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

where

b is the length side of the square

Let

x ---> the length of the original square

The area of the original square is

[tex]A=x^{2}\ in^2[/tex]

The length of the smaller square is

[tex]b=(x-3)\ in[/tex]

The area of the smaller square is

[tex]A=(x-3)^2\ in^2[/tex]

The area of the smaller square is 1/4 the area of the original square

so

[tex](x-3)^2=\frac{1}{4} x^{2}[/tex]

solve for x

[tex]x^2-6x+9=\frac{1}{4} x^{2}[/tex]

Multiply by 4 both sides

[tex]4x^2-24x+36=x^{2}[/tex]

[tex]4x^2-x^2-24x+36=0\\3x^2-24x+36=0[/tex]

Solve the quadratic equation by graphing

using a graphing tool

x=2, x=6

see the attached figure

The solution is x=6 in

Remember that the solution must be greater than 3 inches (because Stacey cuts  3 inches off of the length of the square and 3 inches off of the width)

therefore

The side length of the original square was 6 inches

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