QUESTION IMAGE
Question
- $27z^3 - 9z$
- $x^2 - 6x + 9$
- $15p^3 - 3p - 54$
- $x^2 - 9$
- $8x^2 - 40x + 50$
- $-4x^2 - 10x + 6$
mixed practice b. factor each completely. box your answers!
- $9y^2 - 36$
- $16x^2 - 80x + 100$
- $-x^2 + 18x - 81$
- $64x^2 - 16$
- $\frac{1}{2}y^2 - \frac{1}{2}$
- $30n^2b - 87nb + 30b$
- $2f^2 - 16f$
- $12a^2 - 75$
- $m^4 - 1$
Let's solve problem 16: \(27z^3 - 9z\) using factoring.
Step 1: Find the GCF
The greatest common factor (GCF) of \(27z^3\) and \(9z\) is \(9z\).
\(27z^3 - 9z = 9z(3z^2 - 1)\)
Step 1: Recognize the perfect square trinomial
The expression \(x^2 - 6x + 9\) is a perfect square trinomial of the form \(a^2 - 2ab + b^2 = (a - b)^2\). Here, \(a = x\) and \(b = 3\) (since \(2ab = 2 \cdot x \cdot 3 = 6x\)).
\(x^2 - 6x + 9 = (x - 3)^2\)
Step 1: Find the GCF
The GCF of \(15p^2\), \(-3p\), and \(-54\) is \(3\).
\(15p^2 - 3p - 54 = 3(5p^2 - p - 18)\)
Step 2: Factor the quadratic
Factor \(5p^2 - p - 18\). We need two numbers that multiply to \(5 \cdot (-18) = -90\) and add to \(-1\). These numbers are \(-10\) and \(9\).
\(5p^2 - p - 18 = 5p^2 + 9p - 10p - 18\)
\(= p(5p + 9) - 2(5p + 9)\)
\(= (5p + 9)(p - 2)\)
Step 3: Combine the factors
\(15p^2 - 3p - 54 = 3(5p + 9)(p - 2)\)
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\(\boxed{9z(3z^2 - 1)}\)
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Let's solve problem 17: \(x^2 - 6x + 9\) using factoring.