The problem describes a rectangle $PQRS$ with a square of side $x$ cut out from it. The dimensions of the rectangle are $20$ cm in height and $10 + 10 = 20$ cm in width. The area of the shaded portion (rectangle minus the square) is given as $484 \text{ cm}^2$. We need to find the value of $x$.

AlgebraGeometryAreaQuadratic EquationsRectangleSquare
2025/4/20

1. Problem Description

The problem describes a rectangle PQRSPQRS with a square of side xx cut out from it. The dimensions of the rectangle are 2020 cm in height and 10+10=2010 + 10 = 20 cm in width. The area of the shaded portion (rectangle minus the square) is given as 484 cm2484 \text{ cm}^2. We need to find the value of xx.

2. Solution Steps

The area of the rectangle PQRSPQRS is given by:
Area of rectangle=length×width\text{Area of rectangle} = \text{length} \times \text{width}
Area of rectangle=20 cm×20 cm=400 cm2\text{Area of rectangle} = 20 \text{ cm} \times 20 \text{ cm} = 400 \text{ cm}^2.
The area of the square is given by:
Area of square=x2\text{Area of square} = x^2.
The area of the shaded portion is the area of the rectangle minus the area of the square:
Area of shaded portion=Area of rectangleArea of square\text{Area of shaded portion} = \text{Area of rectangle} - \text{Area of square}
484=400x2484 = 400 - x^2
Now, we solve for x2x^2:
x2=400484x^2 = 400 - 484 is impossible, because x2x^2 cannot be negative. The problem statement is incorrect as stated.
Let's assume the width of rectangle PQRSPQRS is (10+x+10)=(20+x)(10 + x + 10) = (20 + x) cm and height is 20 cm.
Then the area of rectangle PQRSPQRS is:
Arectangle=20(20+x)A_{\text{rectangle}} = 20(20+x)
The area of the square is:
Asquare=x2A_{\text{square}} = x^2
The area of the shaded region is:
Ashaded=ArectangleAsquareA_{\text{shaded}} = A_{\text{rectangle}} - A_{\text{square}}
484=20(20+x)x2484 = 20(20+x) - x^2
484=400+20xx2484 = 400 + 20x - x^2
x220x+84=0x^2 - 20x + 84 = 0
We can factor this quadratic equation:
(x6)(x14)=0(x - 6)(x - 14) = 0
So, x=6x = 6 or x=14x = 14.

3. Final Answer

The possible values of xx are 66 and 1414.
If x=6x = 6, the rectangle has dimensions 20 cm by 26 cm and area = 520 cm2cm^2. The area of the square is 62=36cm26^2=36 cm^2. The shaded area is then 52036=484cm2520 - 36 = 484 cm^2
If x=14x=14, the rectangle has dimensions 20 cm by 34 cm and area = 680 cm2cm^2. The area of the square is 142=196cm214^2=196 cm^2. The shaded area is then 680196=484cm2680 - 196 = 484 cm^2
Final Answer: The values of xx are 6 and 14.

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