Math Problem Statement

The area of the vegetable garden in the form shown in the figure was 80 m². A fence with a 1 m wide iron net was built around the green land. How many meters of wire are needed?

Solution

From the image, the question states:

  • The area of the vegetable garden is 80 m².
  • A fence with a 1 m wide iron net was built around the green land.
  • The shape in the diagram suggests a rectangular garden.
  • The dimensions of the garden are marked as x+2x + 2 and xx meters.

The goal is to find how many meters of wire (presumably the perimeter) are needed for the fence.

Step-by-step solution:

  1. Area of the garden: The area of the rectangle is given by the formula for the area of a rectangle: Area=length×width\text{Area} = \text{length} \times \text{width} Here, the length is x+2x + 2 and the width is xx. Therefore, we have: (x+2)×x=80(x + 2) \times x = 80 Expanding this equation: x2+2x=80x^2 + 2x = 80 Rearranging: x2+2x80=0x^2 + 2x - 80 = 0 Now we solve this quadratic equation using the quadratic formula: x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} where a=1a = 1, b=2b = 2, and c=80c = -80.

    Plugging in the values: x=2±224(1)(80)2(1)x = \frac{-2 \pm \sqrt{2^2 - 4(1)(-80)}}{2(1)} x=2±4+3202x = \frac{-2 \pm \sqrt{4 + 320}}{2} x=2±3242x = \frac{-2 \pm \sqrt{324}}{2} x=2±182x = \frac{-2 \pm 18}{2} So, we have two possible solutions: x=2+182=8orx=2182=10x = \frac{-2 + 18}{2} = 8 \quad \text{or} \quad x = \frac{-2 - 18}{2} = -10

    Since the width cannot be negative, we take x=8x = 8.

  2. Dimensions of the garden:

    • Width: x=8x = 8 meters
    • Length: x+2=10x + 2 = 10 meters
  3. Perimeter: The perimeter of a rectangle is given by: Perimeter=2(length+width)=2(10+8)=2(18)=36meters\text{Perimeter} = 2(\text{length} + \text{width}) = 2(10 + 8) = 2(18) = 36 \, \text{meters}

Thus, 36 meters of wire are needed to fence the garden.


Do you have any questions or would you like more details?

Related questions:

  1. How do you solve more complex quadratic equations?
  2. What are some other methods to calculate the perimeter of irregular shapes?
  3. How does the quadratic formula work for non-integer solutions?
  4. Could this problem be solved using a different approach?
  5. What would happen if the garden had a different shape, like a circle or triangle?

Tip:

Always ensure that the dimensions of any physical object make sense within the context of the problem. Negative values often indicate extraneous solutions.

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Math Problem Analysis

Mathematical Concepts

Geometry
Algebra
Quadratic Equations
Perimeter Calculation

Formulas

Area of a rectangle = length × width
Quadratic equation: ax^2 + bx + c = 0
Perimeter of a rectangle = 2(length + width)

Theorems

Quadratic Formula

Suitable Grade Level

Grades 7-9