Math Problem Statement

The length and breadth of a rectangle are (x + 10) meters and (x + 6) meters respectively. The area of the rectangle is 396 m². If the length of the rectangle is increased by 2 meters, then find the perimeter of the rectangle.

Solution

Let's solve the problem step by step.

Problem Details:

  • The length of the rectangle: x+10x + 10 meters.
  • The breadth of the rectangle: x+6x + 6 meters.
  • Area of the rectangle: 396m2396 \, \text{m}^2.
  • After increasing the length by 2 meters, we are to find the perimeter of the rectangle.

Step 1: Use the area formula to find xx.

The area of a rectangle is given by: Area=Length×Breadth\text{Area} = \text{Length} \times \text{Breadth} Substitute the given values: 396=(x+10)(x+6)396 = (x + 10)(x + 6)

Expand: 396=x2+6x+10x+60396 = x^2 + 6x + 10x + 60 396=x2+16x+60396 = x^2 + 16x + 60

Rearrange into standard quadratic form: x2+16x+60396=0x^2 + 16x + 60 - 396 = 0 x2+16x336=0x^2 + 16x - 336 = 0


Step 2: Solve for xx using the quadratic formula.

The quadratic formula is: x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} Here, a=1a = 1, b=16b = 16, and c=336c = -336. Substituting: x=16±1624(1)(336)2(1)x = \frac{-16 \pm \sqrt{16^2 - 4(1)(-336)}}{2(1)} x=16±256+13442x = \frac{-16 \pm \sqrt{256 + 1344}}{2} x=16±16002x = \frac{-16 \pm \sqrt{1600}}{2} x=16±402x = \frac{-16 \pm 40}{2}

Calculate the two possible solutions: x=16+402=242=12x = \frac{-16 + 40}{2} = \frac{24}{2} = 12 x=16402=562=28x = \frac{-16 - 40}{2} = \frac{-56}{2} = -28

Since xx represents a length, it must be positive: x=12x = 12


Step 3: Calculate the new length and breadth.

  • Original length: x+10=12+10=22mx + 10 = 12 + 10 = 22 \, \text{m}.
  • Original breadth: x+6=12+6=18mx + 6 = 12 + 6 = 18 \, \text{m}.

After increasing the length by 2 meters:

  • New length: 22+2=24m22 + 2 = 24 \, \text{m}.
  • New breadth remains 18m18 \, \text{m}.

Step 4: Find the new perimeter.

The perimeter of a rectangle is: Perimeter=2(Length+Breadth)\text{Perimeter} = 2(\text{Length} + \text{Breadth}) Substitute the values: Perimeter=2(24+18)=2(42)=84m\text{Perimeter} = 2(24 + 18) = 2(42) = 84 \, \text{m}


Final Answer:

The perimeter of the rectangle is 84 meters.


Would you like further explanation or have any related questions? Here are five possible related queries to explore:

  1. How do we verify the solution for xx using the original area?
  2. What would the perimeter be if the breadth were also increased by 2 meters?
  3. How does the quadratic formula work, and why do we discard negative solutions in this case?
  4. Could this problem be solved by completing the square instead of using the quadratic formula?
  5. What happens to the area if both the length and breadth are increased by 2 meters?

Tip: Always verify your results by substituting back into the original equations!

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Math Problem Analysis

Mathematical Concepts

Quadratic Equations
Algebra
Geometry

Formulas

Area of a rectangle = Length × Breadth
Quadratic equation formula: ax² + bx + c = 0
Perimeter of a rectangle = 2(Length + Breadth)

Theorems

Quadratic formula

Suitable Grade Level

Grades 8-10