Factor u³ + 125 completely.

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Understand the Problem

The question is asking us to factor the expression u³ + 125 completely. This involves recognizing it as a sum of cubes and applying the appropriate factoring formula.

Answer

The completely factored form of $u^3 + 125$ is: $(u + 5)(u^2 - 5u + 25)$.
Answer for screen readers

The completely factored form of the expression $u^3 + 125$ is: $ (u + 5)(u^2 - 5u + 25) $.

Steps to Solve

  1. Recognize the Sum of Cubes Formula

The expression $u^3 + 125$ can be seen as a sum of cubes. Recall the sum of cubes factoring formula: $$ a^3 + b^3 = (a + b)(a^2 - ab + b^2) $$

In this case, $a = u$ and $b = 5$ since $125 = 5^3$.

  1. Identify a and b

Set $a = u$ and $b = 5$. Now we can apply the sum of cubes formula.

  1. Apply the Formula

Using the formula, we have: $$ u^3 + 125 = (u + 5)(u^2 - u \cdot 5 + 5^2) $$

This simplifies to: $$ u^3 + 125 = (u + 5)(u^2 - 5u + 25) $$

  1. Final Factorization

Thus, the completely factored form of $u^3 + 125$ is: $$ (u + 5)(u^2 - 5u + 25) $$

The completely factored form of the expression $u^3 + 125$ is: $ (u + 5)(u^2 - 5u + 25) $.

More Information

The expression $u^3 + 125$ can be recognized as a sum of cubes, which is a common form in algebra that can be factored using the sum of cubes formula. This is significant in various areas of mathematics, especially in polynomial factorization.

Tips

  • Forgetting the Formula: A common mistake is not recognizing the sum of cubes form. Always check if the expression fits the $a^3 + b^3$ format.
  • Incorrectly Identifying b: Ensure you correctly identify $b$ when you rewrite constants as cubes, like recognizing $125$ as $5^3$.

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