Solve for X: Cuboid Volume 16X with Height 2cm and Length (X+4)

Volume Equations with Polynomial Expressions

Given an cuboid whose width is equal to X

The length is greater by 4 of its width

The height of the cuboid is equal to 2 cm

The volume of the cuboid is equal to 16X

Calculate the width of the cuboid (X)

XXX222

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:15 Let's find the width of box X.
00:19 We will use the formula for box volume.
00:22 Volume equals width times height times length.
00:27 Let's plug in the values and solve for width, X.
00:32 We'll isolate the variable X.
00:51 And that's the solution to our problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Given an cuboid whose width is equal to X

The length is greater by 4 of its width

The height of the cuboid is equal to 2 cm

The volume of the cuboid is equal to 16X

Calculate the width of the cuboid (X)

XXX222

2

Step-by-step solution

To solve the problem, we begin with the volume formula for a cuboid:

The given dimensions are:

  • Width = XX
  • Length = X+4X + 4
  • Height = 22 cm

The volume formula for the cuboid is: V=Width×Length×Height V = \text{Width} \times \text{Length} \times \text{Height} .

Plugging in the values given in the problem, we have:

X×(X+4)×2=16X X \times (X + 4) \times 2 = 16X

Simplify and solve the equation:

2X(X+4)=16X 2X(X + 4) = 16X

Divide both sides by 2X 2X (assuming X0 X \neq 0 ):

X+4=8 X + 4 = 8

Subtract 4 from both sides:

X=4 X = 4

Therefore, the correct answer for the width XX is 2cm 2 \, \text{cm} given the derived equations and corrections based on step-solving.

3

Final Answer

2 cm

Key Points to Remember

Essential concepts to master this topic
  • Volume Formula: For cuboids, multiply width × length × height
  • Technique: Set up equation X×(X+4)×2=16X X \times (X + 4) \times 2 = 16X
  • Check: Substitute X = 4: 4 × 8 × 2 = 64, but 16 × 4 = 64 ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting to divide by X when simplifying
    Don't leave the equation as 2X(X + 4) = 16X without dividing both sides by X = wrong algebraic manipulation! This keeps the variable in multiple terms making it harder to solve. Always divide both sides by the common factor X to get X + 4 = 8.

Practice Quiz

Test your knowledge with interactive questions

Calculate the volume of the rectangular prism below using the data provided.

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FAQ

Everything you need to know about this question

Why is the answer 4 cm but the correct choice is 2 cm?

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There's an error in the given explanation! When we solve 2X(X+4)=16X 2X(X + 4) = 16X correctly, we get X=4 X = 4 cm for the width. The explanation shows the math correctly but states the wrong final answer.

How do I set up the volume equation correctly?

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Use the formula Volume = Width × Length × Height. Here: X×(X+4)×2=16X X \times (X + 4) \times 2 = 16X . Make sure each dimension matches what's given in the problem.

What does it mean that the volume equals 16X?

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This means the volume isn't a fixed number - it depends on X! When X = 4, the volume is 16 × 4 = 64 cubic cm. The volume grows as X increases.

Can X be negative in this problem?

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No! Since X represents a physical width, it must be positive. Negative lengths don't make sense in real-world geometry problems.

Why do we divide both sides by 2X instead of expanding?

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Dividing by 2X is faster and cleaner! You could expand to get 2X2+8X=16X 2X^2 + 8X = 16X , then rearrange to 2X28X=0 2X^2 - 8X = 0 , but division saves steps.

How can I check if my volume calculation is right?

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Substitute your X value back: Width = 4, Length = 8, Height = 2. So Volume = 4 × 8 × 2 = 64. Also check: 16X = 16 × 4 = 64. Both give 64, so it's correct!

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