Rectangle Perimeter Problem: Solving for X When One Side is 2x

The perimeter of the rectangle below is 12.

Calculate x.
AAABBBCCCDDDx2x

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:03 Opposite sides are equal in a rectangle
00:21 The perimeter of the rectangle equals the sum of its sides
00:32 We'll substitute appropriate values and solve for X
00:48 Collect like terms
01:01 Isolate X
01:10 And this is the solution to the problem

Step-by-step written solution

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1

Understand the problem

The perimeter of the rectangle below is 12.

Calculate x.
AAABBBCCCDDDx2x

2

Step-by-step solution

To solve this problem, we will determine x x using the perimeter formula for a rectangle. The steps are as follows:

  • Step 1: Set up the perimeter equation for this problem using the formula P=2(l+w) P = 2(l + w) .
  • Step 2: Identify the given dimensions: l=2x l = 2x and w=x w = x .
  • Step 3: Substitute these dimensions into the perimeter equation: 2(2x+x)=12 2(2x + x) = 12 .
  • Step 4: Simplify the equation to solve for x x .

Now, let's follow these steps:

Step 1: The perimeter P=12 P = 12 units. Thus, we use the equation:

2(l+w)=12 2(l + w) = 12

Step 2: Substitute the known values of length and width:

2(2x+x)=12 2(2x + x) = 12

Step 3: Simplify the equation inside the parentheses:

2(3x)=12 2(3x) = 12

Step 4: Divide both sides by 2 to solve for x x :

3x=6 3x = 6

Finally, divide by 3:

x=2 x = 2

Therefore, the solution to the problem is x=2 x = 2 .

3

Final Answer

2

Practice Quiz

Test your knowledge with interactive questions

Look at the rectangle ABCD below.

Side AB is 6 cm long and side BC is 4 cm long.

What is the area of the rectangle?
666444AAABBBCCCDDD

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