Math Problem Statement

A rectangular pool 12 meters by 8 meters is surrounded by a walkway of width x meters. At what value of x will the area of the walkway equal the area of the pool?

Solution

To solve this problem, we need to find the value of xx for which the area of the walkway equals the area of the pool.

Step 1: Find the Area of the Pool

The pool is rectangular with dimensions 12meters×8meters12 \, \text{meters} \times 8 \, \text{meters}. Area of the pool=12×8=96square meters\text{Area of the pool} = 12 \times 8 = 96 \, \text{square meters}

Step 2: Determine the Dimensions of the Outer Rectangle (Pool + Walkway)

The walkway surrounds the pool on all sides with a width of xx meters. Therefore:

  • The length of the outer rectangle (including the walkway) is 12+2x12 + 2x.
  • The width of the outer rectangle (including the walkway) is 8+2x8 + 2x.

Step 3: Calculate the Area of the Outer Rectangle

The area of the outer rectangle is: Area of the outer rectangle=(12+2x)(8+2x)\text{Area of the outer rectangle} = (12 + 2x)(8 + 2x)

Expanding this: (12+2x)(8+2x)=96+24x+16x+4x2=96+40x+4x2(12 + 2x)(8 + 2x) = 96 + 24x + 16x + 4x^2 = 96 + 40x + 4x^2

So, the area of the outer rectangle is: 4x2+40x+964x^2 + 40x + 96

Step 4: Calculate the Area of the Walkway

The area of the walkway is the area of the outer rectangle minus the area of the pool: Area of the walkway=(4x2+40x+96)96=4x2+40x\text{Area of the walkway} = (4x^2 + 40x + 96) - 96 = 4x^2 + 40x

Step 5: Set Up the Equation

We want the area of the walkway to equal the area of the pool, so: 4x2+40x=964x^2 + 40x = 96

Step 6: Solve for xx

Divide each term by 4 to simplify: x2+10x=24x^2 + 10x = 24

Rewrite as a standard quadratic equation: x2+10x24=0x^2 + 10x - 24 = 0

Solve this quadratic equation using the quadratic formula: x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} where a=1a = 1, b=10b = 10, and c=24c = -24.

[ x = \frac{-10 \pm \sqrt{10^2 + 4 \cdot 24}}{2 \cdot

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Math Problem Analysis

Mathematical Concepts

Algebra
Geometry
Quadratic Equations

Formulas

Area of rectangle = length × width
Quadratic formula: x = (-b ± √(b^2 - 4ac)) / 2a

Theorems

Quadratic formula

Suitable Grade Level

Grades 9-11