Question

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Grace, Chelsea, and Roan are simplifying the same polynomial expression. Which student’s work is correct and why?

Grace Chelsea Roan
3(2 − x) − 2(6x − 8) 3(2 − x) − 2(6x − 8) 3(2 − x) − 2(6x − 8)
= 6 − 3x − 12x + 16 = 6 − 3x − 12x – 16 = 6 − 3x + 12x – 16
= -3x − 12x + 16 + 6 = -3x − 12x − 16 + 6 = -3x + 12x − 16 + 6
= -15x + 22 = -15x − 10 = 9x − 10

Answers

GPT-4o mini
Let's analyze each student's work step by step to determine whose simplification of the polynomial expression is correct.

Starting with the original expression that all three students used:

\[ 3(2 − x) − 2(6x − 8) \]

1. **Distributing the terms**:
- For Grace:
\[ 3(2) - 3(x) - 2(6x) + 2(8) \]
\[ = 6 - 3x - 12x + 16 \]
- For Chelsea:
\[ 3(2) - 3(x) - 2(6x) + 2(8) \]
\[ = 6 - 3x - 12x - 16 \]
- For Roan:
\[ 3(2) - 3(x) - 2(6x) + 2(8) \]
\[ = 6 - 3x + 12x - 16 \]

2. **Combining like terms**:
- Grace's terms:
\[ 6 + 16 - 3x - 12x = 22 - 15x \rightarrow -15x + 22 \]
- Chelsea's terms:
\[ 6 - 16 - 3x - 12x = -10 - 15x \rightarrow -15x - 10 \]
- Roan's terms:
\[ 6 - 16 - 3x + 12x = -10 + 9x \rightarrow 9x - 10 \]

Now, we check the combination of like terms step:

For Grace’s calculation:
- Combine numerical constants: \( 6 + 16 = 22 \)
- Combine \( x \) terms: \( -3x - 12x = -15x \)
Thus, Grace’s final simplified form is \(-15x + 22\).

For Chelsea’s calculation:
- Combine numerical constants: \( 6 - 16 = -10 \)
- Combine \( x \) terms: \( -3x - 12x = -15x \)
So, Chelsea's final form is \(-15x - 10\).

For Roan’s calculation:
- Combine numerical constants: \( 6 - 16 = -10 \)
- Combine \( x \) terms: \( -3x + 12x = 9x \)
His final form is \(9x - 10\).

3. **Final comparison**:
- Grace: \(-15x + 22\)
- Chelsea: \(-15x - 10\)
- Roan: \(9x - 10\)

The correct simplification of the polynomial expression results in \(-15x + 22\). Thus, **Grace’s work is correct**. Chelsea and Roan made mistakes in their simplifications either by incorrectly distributing the terms or combining like terms. Grace maintained the correct distribution and combination throughout her work.

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