Question
Factor the expression: \( 8y^{3} - 1 \)
Ask by Lee Montgomery. in South Africa
Jan 26,2025
Real Tutor Solution
Tutor-Verified Answer
Answer
The expression \( 8y^{3} - 1 \) factors to \( (2y - 1)(4y^2 + 2y + 1) \).
Solution
To factor the expression \( 8y^{3} - 1 \), we can recognize it as a **difference of cubes**. Here's how to proceed:
1. **Identify the Cubes:**
- \( 8y^3 = (2y)^3 \)
- \( 1 = 1^3 \)
2. **Apply the Difference of Cubes Formula:**
The formula for factoring a difference of cubes is:
\[
a^3 - b^3 = (a - b)(a^2 + ab + b^2)
\]
Here, \( a = 2y \) and \( b = 1 \).
3. **Substitute into the Formula:**
\[
8y^3 - 1 = (2y)^3 - 1^3 = (2y - 1)\left( (2y)^2 + (2y)(1) + 1^2 \right)
\]
Simplifying further:
\[
(2y - 1)(4y^2 + 2y + 1)
\]
4. **Check for Further Factoring:**
The quadratic \( 4y^2 + 2y + 1 \) does not factor neatly over the real numbers because its discriminant is negative:
\[
\Delta = (2)^2 - 4(4)(1) = 4 - 16 = -12
\]
Since the discriminant is negative, the quadratic cannot be factored further using real numbers.
**Final Factored Form:**
\[
8y^{3} - 1 = (2y - 1)(4y^2 + 2y + 1)
\]
**Answer:**
After factoring, the expression is (2 y – 1) multiplied by (4y² + 2y + 1). Thus,
(2y−1)(4y²+2y+1)
Reviewed and approved by the UpStudy tutoring team
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Extra Insights
To factor the expression \( 8y^{3} - 1 \), we can recognize it as a difference of cubes. The formula for factoring a difference of cubes is \( a^3 - b^3 = (a - b)(a^2 + ab + b^2) \). Here, we can set \( a = 2y \) (since \( (2y)^3 = 8y^3 \)) and \( b = 1 \) (since \( 1^3 = 1 \)). Using the formula, we get: \[ 8y^{3} - 1 = (2y - 1)((2y)^2 + (2y)(1) + (1)^2) \] This simplifies to: \[ (2y - 1)(4y^2 + 2y + 1) \] Thus, the factored form of \( 8y^{3} - 1 \) is \( (2y - 1)(4y^2 + 2y + 1) \). Happy factoring!