Solve for X: Trapezoid Perimeter with Side Lengths 10x+5 and 10x+4

Perimeter Problems with Variable Expressions

Calculate x in the trapezoid below.

P = Perimeter
10x+510x+510x+5xxx10x+410x+410x+4p=55x+2

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Step-by-step written solution

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1

Understand the problem

Calculate x in the trapezoid below.

P = Perimeter
10x+510x+510x+5xxx10x+410x+410x+4p=55x+2

2

Step-by-step solution

To calculate x x in the trapezoid, start by using the formula for the perimeter, which is the sum of all sides.

The given sides of the trapezoid are: - One side as 10x+5 10x + 5 - Another side as 10x+4 10x + 4 - A third side as x+2 x + 2 - The fourth side as x x

The formula for the perimeter is: P=(10x+5)+(10x+4)+(x+2)+x P = (10x + 5) + (10x + 4) + (x + 2) + x

Substitute the given perimeter, 55, into the equation:

55=(10x+5)+(10x+4)+(x+2)+x 55 = (10x + 5) + (10x + 4) + (x + 2) + x

Simplify the equation by combining like terms:

55=10x+5+10x+4+x+2+x 55 = 10x + 5 + 10x + 4 + x + 2 + x

55=22x+11 55 = 22x + 11

Subtract 11 from both sides to isolate terms involving x x :

44=22x 44 = 22x

Divide both sides by 22 to solve for x x :

x=2 x = 2

Thus, the value of x x that satisfies the equation is 2 \boxed{2} .

3

Final Answer

2

Key Points to Remember

Essential concepts to master this topic
  • Perimeter Formula: Add all four sides of the trapezoid together
  • Technique: Combine like terms: 22x + 11 = 55 becomes 22x = 44
  • Check: Substitute x = 2: (20+5)+(20+4)+(2+2)+2 = 55 ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting to include all four sides in perimeter calculation
    Don't add only the labeled sides and ignore others = incomplete perimeter! This gives you too small a total and wrong value for x. Always identify and add all four sides of the trapezoid, even if some seem obvious.

Practice Quiz

Test your knowledge with interactive questions

Calculate the perimeter of the trapezoid according to the following data:

777101010777121212AAABBBCCCDDD

FAQ

Everything you need to know about this question

How do I know which sides to add for the perimeter?

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The perimeter includes all four sides of the trapezoid! Look at the diagram carefully - you should see four different side lengths, even if some look similar.

What does 'combine like terms' mean exactly?

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Like terms have the same variable with the same power. So 10x + 10x + x + x = 22x, and constants 5 + 4 + 2 = 11. Group them separately!

Why do we set the expression equal to 55?

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The problem states that P = 55, meaning the perimeter equals 55. So our expression for perimeter (10x+5)+(10x+4)+(x+2)+x must equal 55.

Can I solve this without combining like terms first?

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Technically yes, but it's much harder! Combining like terms first simplifies 10x+5+10x+4+x+2+x 10x + 5 + 10x + 4 + x + 2 + x to 22x+11 22x + 11 , making the algebra much easier.

How can I check if x = 2 is really correct?

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Substitute x = 2 into each side length:

  • 10(2)+5 = 25
  • 10(2)+4 = 24
  • 2+2 = 4
  • 2 = 2
Add them: 25+24+4+2 = 55 ✓

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