Q. Factor out the greatest common factor (GCF) from the expression: \(8x^{2} – 12x + 16\).
Answer
The coefficients 8, −12, 16 have GCF 4 and the smallest power of x is x^0, so factor out 4:
\[8x^2-12x+16 = 4(2x^2-3x+4).\]
Detailed Explanation
Factor out the greatest common factor (GCF) from the expression
Given expression: \(8x^{2} – 12x + 16\)
- List the coefficients and variable parts separately.Coefficients: 8, −12, 16.
Variable parts: \(x^{2}\), \(x\), and the constant (which is \(x^{0}\)). - Find the greatest common divisor of the coefficients.Compute the GCD of 8, 12, and 16. Prime factorizations:
\(8 = 2^{3}\), \(12 = 2^{2}\cdot 3\), \(16 = 2^{4}\).
The common prime power is \(2^{2}\), so GCD = 4.
- Determine the common variable factor.The terms have variable powers \(x^{2}\), \(x^{1}\), and \(x^{0}\). The smallest exponent present is 0, so no positive power of \(x\) is common to all terms. Therefore the GCF does not include \(x\).
- Write the GCF and divide each term by the GCF.GCF = 4.
Divide each term by 4:
\(\dfrac{8x^{2}}{4} = 2x^{2}\), \(\dfrac{-12x}{4} = -3x\), \(\dfrac{16}{4} = 4\).
- Form the factored expression and verify by distribution.Factored form: \(4\bigl(2x^{2} – 3x + 4\bigr)\).
Verification by distributing 4:
\(4\cdot 2x^{2} = 8x^{2}\), \(4\cdot (-3x) = -12x\), \(4\cdot 4 = 16\). These reproduce the original expression.
Final answer: \(4\bigl(2x^{2} – 3x + 4\bigr)\)
See full solution
Algebra FAQs
What is the GCF of \(8x^2 - 12x + 16\)?
The greatest common factor is 4, since 8, 12, and 16 are all divisible by 4 and the variable \(x\) is not common to every term.
How do I factor out the GCF?
Divide every term by 4: \(8x^2 - 12x + 16 = 4(2x^2 - 3x + 4)\)..
Can the quadratic inside be factored further over the integers?.
No. The discriminant is \( \Delta = (-3)^2 - 4(2)(4) = -23 < 0 \), so it has no real or integer linear factors..
Why doesn’t the GCF include \(x\)?
\( \text{GCF must divide every term;} \) the constant term \(16\) has no \(x\) factor, so \(x\) is not common to all terms and cannot be included.
How can I check the factorization is correct?
Expand the factor: \(4(2x^2 - 3x + 4) = 8x^2 - 12x + 16\). Matching the original confirms the factorization is correct.
Does factoring out the GCF change the polynomial’s roots?
Does factoring out the GCF change the polynomial’s roots?
Could I factor out a negative GCF instead?
Yes: \(8x^2 - 12x + 16 = -4(-2x^2 + 3x - 4)\). Conventions usually prefer a positive GCF, but a negative one is valid.
How would the expression factor over the complex numbers?
Over complex numbers: \(8x^2 - 12x + 16 = 8\bigl(x - \tfrac{3+i\sqrt{23}}{4}\bigr)\bigl(x - \tfrac{3-i\sqrt{23}}{4}\bigr)\).
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