Chapter 5: Problem 69
Factor each trinomial. Factor out the GCF first. See Example 9 or Example 12. $$ 10 b^{6}-19 b^{4}+6 b^{2} $$
Short Answer
Expert verified
The trinomial factors to \(b^2(5b^2 - 2)(2b^2 - 3)\).
Step by step solution
01
Identify the Greatest Common Factor (GCF)
The given trinomial is \(10b^6 - 19b^4 + 6b^2\). First, observe each term to determine the greatest common factor. Each term contains \(b^2\), so the GCF is \(b^2\).
02
Factor out the GCF
Factor \(b^2\) out of each term in the trinomial. This gives:\[ b^2(10b^4 - 19b^2 + 6) \]
03
Set up for Factoring the Quadratic
Now, consider the quadratic inside the parentheses: \(10b^4 - 19b^2 + 6\). Rewrite this as a quadratic by letting \(x = b^2\), so it becomes \(10x^2 - 19x + 6\).
04
Factor the Quadratic Expression
Look for two numbers that multiply to \(10 \times 6 = 60\) and add up to \(-19\). These numbers are \(-15\) and \(-4\). Rewrite the middle term using these two numbers:\[ 10x^2 - 15x - 4x + 6 \]
05
Factor by Grouping
Group the terms to assist in factoring:\[ (10x^2 - 15x) + (-4x + 6) \]Factor the common factor out of each group:\[ 5x(2x - 3) - 2(2x - 3) \]Notice \((2x - 3)\) is a common factor:\[ (5x - 2)(2x - 3) \]
06
Substitute back in terms of b
Replace \(x\) with \(b^2\) in the factored form:\[ (5b^2 - 2)(2b^2 - 3) \]
07
Combine with the GCF
Don't forget to combine this with the GCF factored out earlier. The full factored form is:\[ b^2(5b^2 - 2)(2b^2 - 3) \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Greatest Common Factor
When we start factoring any expression, it's essential to find the **Greatest Common Factor (GCF)**. The GCF is the largest factor that divides all terms of the expression evenly. In the trinomial \(10b^6 - 19b^4 + 6b^2\), we examine each term to identify any common factors.
Every term in the given trinomial shares a common factor of \(b^2\), so \(b^2\) is the GCF. Factoring out \(b^2\) simplifies the trinomial by reducing each exponent by 2. We get:
Every term in the given trinomial shares a common factor of \(b^2\), so \(b^2\) is the GCF. Factoring out \(b^2\) simplifies the trinomial by reducing each exponent by 2. We get:
- Original Trinomial: \(10b^6\) - \(19b^4\) + \(6b^2\)
- Factored by GCF: \(b^2(10b^4 - 19b^2 + 6)\)
Factoring by Grouping
Once we factor out the GCF, we often need further techniques to simplify the remaining expression. Factoring by grouping is a strategic approach, especially useful for quadratic expressions after dealing with the GCF.
After replacing the variables in terms that are easier to handle (like letting \(x = b^2\)), we convert our expression to \(10x^2 - 19x + 6\). Now, we can use factoring by grouping:
After replacing the variables in terms that are easier to handle (like letting \(x = b^2\)), we convert our expression to \(10x^2 - 19x + 6\). Now, we can use factoring by grouping:
- Split the middle term using numbers that multiply to a(x) \(\cdot\) c: Here, \(10 \cdot 6 = 60\). Two numbers that work are \(-15\) and \(-4\) (adding to \(-19\))
- Rewrite the expression: \(10x^2 - 15x - 4x + 6\)
- Group and factor: \((10x^2 - 15x) + (-4x + 6)\)
- Factor out the GCF from each group: \(5x(2x - 3) - 2(2x - 3)\)
- Notice the common factor: \((2x - 3)\), leading to \((5x - 2)(2x - 3)\)
Quadratic Expressions
Quadratic expressions are typically in the form \(ax^2 + bx + c\). These expressions are foundational in algebra and can often be factored down into binomials. In our case, after substituting \(x = b^2\), the expression changes to a standard quadratic form \(10x^2 - 19x + 6\).
To factor a quadratic expression, we identify two numbers that solve:
After successful grouping and factoring, substituting back the original variables (in terms of \(b\)) gives us the complete factorization:
To factor a quadratic expression, we identify two numbers that solve:
- Multiply to \(a \cdot c\)
- Add to \(b\)
After successful grouping and factoring, substituting back the original variables (in terms of \(b\)) gives us the complete factorization:
- \((5b^2 - 2)(2b^2 - 3)\)