James says

x+2 is a factor of x^3-3x+2
. Susan says he is incorrect and that x+2
is not a factor of x^3-3x+2
.

Determine which student is correct and explain how you know by using concepts learned in Unit 7. Also, show any work that is needed to support your explanation.

User Icon for Bot GPT 4-o mini Bot GPT 4-o mini answered
3 hours ago

To determine whether \( x + 2 \) is a factor of \( x^3 - 3x + 2 \), we can use the Factor Theorem, which states that \( (x - c) \) is a factor of a polynomial \( P(x) \) if and only if \( P(c) = 0 \). In our case, we can rewrite \( x + 2 \) as \( x - (-2) \), indicating that we should check \( P(-2) \).

Let's evaluate \( P(-2) = (-2)^3 - 3(-2) + 2 \).

  1. Calculate \( (-2)^3 \): \[ (-2)^3 = -8 \]

  2. Calculate \( -3(-2) \): \[ -3(-2) = 6 \]

  3. Now substitute these values back into \( P(-2) \): \[ P(-2) = -8 + 6 + 2 \]

  4. Combine the terms: \[ P(-2) = -8 + 6 + 2 = -8 + 8 = 0 \]

Since \( P(-2) = 0 \), by the Factor Theorem, \( x + 2 \) is indeed a factor of \( x^3 - 3x + 2 \).

Conclusion

James is correct; \( x + 2 \) is a factor of \( x^3 - 3x + 2 \). We confirmed this by evaluating the polynomial at \( x = -2 \) and showing that it equals 0.