Solve for X: Triangle with Sides 2X, 3X, and 3.5X Having 17cm Perimeter

Perimeter Equations with Variable Coefficients

The perimeter of the triangle ABC is equal to 17 cm.

Calculate X.

2X2X2X3.5X3.5X3.5X3X3X3XAAABBBCCC

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Determine the value of X
00:03 The perimeter of the triangle equals the sum of its sides
00:07 Substitute in the relevant values according to the given data and proceed to solve for X
00:16 Collect like terms
00:20 Substitute in the perimeter value and isolate the unknown X
00:26 This is the solution

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

The perimeter of the triangle ABC is equal to 17 cm.

Calculate X.

2X2X2X3.5X3.5X3.5X3X3X3XAAABBBCCC

2

Step-by-step solution

The solution involves calculating the unknown X X using the perimeter provided for the triangle ABC:

  • The equation representing the perimeter of triangle ABC is:
    2X+3X+3.5X=17 2X + 3X + 3.5X = 17 .
  • Combine like terms:
    8.5X=17 8.5X = 17 .
  • To find X X , divide both sides by 8.5:
    X=178.5 X = \frac{17}{8.5} .
  • Calculate the division:
    X=2 X = 2 .
  • Verify by checking the perimeter with X=2 X = 2 :
    2×2+3×2+3.5×2=4+6+7=17 2 \times 2 + 3 \times 2 + 3.5 \times 2 = 4 + 6 + 7 = 17 , which matches the given perimeter.

Thus, the value of X X is 2 2 .

3

Final Answer

2

Key Points to Remember

Essential concepts to master this topic
  • Perimeter Formula: Add all sides to get total perimeter
  • Combining Terms: 2X+3X+3.5X=8.5X 2X + 3X + 3.5X = 8.5X
  • Verification: Check by substituting: 2(2)+3(2)+3.5(2)=4+6+7=17 2(2) + 3(2) + 3.5(2) = 4 + 6 + 7 = 17

Common Mistakes

Avoid these frequent errors
  • Adding coefficients incorrectly when combining like terms
    Don't add 2 + 3 + 3.5 = 8.5 then multiply by X = wrong setup! This treats X as a separate multiplier instead of part of each term. Always combine like terms: 2X + 3X + 3.5X = 8.5X, then solve 8.5X = 17.

Practice Quiz

Test your knowledge with interactive questions

Angle A is equal to 30°.
Angle B is equal to 60°.
Angle C is equal to 90°.

Can these angles form a triangle?

FAQ

Everything you need to know about this question

Why do all the sides have X in them?

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The sides are proportional to each other! This means they're all related by the same scaling factor X. When X = 2, the sides become 4 cm, 6 cm, and 7 cm.

How do I combine 2X + 3X + 3.5X?

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Think of X as a common factor: 2X + 3X + 3.5X = (2 + 3 + 3.5)X = 8.5X. It's like combining 2 apples + 3 apples + 3.5 apples = 8.5 apples!

What if I get a decimal answer for X?

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Decimal answers are completely normal! In this problem, X = 2 is a whole number, but many similar problems have decimal solutions. Always check your work by substituting back.

Can triangles have sides with decimals like 3.5X?

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Absolutely! Side lengths can be any positive number, including decimals. When X = 2, the side 3.5X becomes 7 cm, which is a perfectly valid triangle side.

How do I know if my triangle is valid?

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Check the triangle inequality: the sum of any two sides must be greater than the third side. With sides 4, 6, and 7: 4+6>7 ✓, 4+7>6 ✓, 6+7>4 ✓

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