Réponse:
**a. \(a \cdot x - 4(3x + 2)\) :**
\[ a \cdot x - 4 \cdot 3x - 4 \cdot 2 \]
\[ a \cdot x - 12x - 8 \]
**b. \(5x - (x + 1)(6x - 2)\) :**
\[ 5x - (x \cdot 6x - x \cdot 2 + 1 \cdot 6x - 1 \cdot 2) \]
\[ 5x - (6x^2 - 2x + 6x - 2) \]
\[ 5x - 6x^2 + 8x - 2 \]
**c. \(6 - 3(2x - 1)\) :**
\[ 6 - 3 \cdot 2x + 3 \cdot 1 \]
\[ 6 - 6x + 3 \]
**d. \(3(x - 2)(2x + 5)\) :**
\[ 3 \cdot (x \cdot 2x + x \cdot 5 - 2 \cdot 2x - 2 \cdot 5) \]
\[ 3 \cdot (2x^2 + 5x - 4x - 10) \]
\[ 3 \cdot (2x^2 + x - 10) \]
**e. \( (x - 2)(x - 3) \) :**
\[ x \cdot x - x \cdot 3 - 2 \cdot x + 2 \cdot 3 \]
\[ x^2 - 3x - 6 \]
**f. \(5(2x - 3)(x - 1)\) :**
\[ 5 \cdot (2x \cdot x - 2x \cdot 1 - 3 \cdot x + 3 \cdot 1) \]
\[ 5 \cdot (2x^2 - 2x - 3x + 3) \]
\[ 5 \cdot (2x^2 - 5x + 3) \]
**g. \(x(x - 1)(x + 2)\) :**
\[ x \cdot (x \cdot x + x \cdot 2 - 1 \cdot x - 1 \cdot 2) \]
\[ x \cdot (x^2 + 2x - x - 2) \]
\[ x \cdot (x^2 + x - 2) \]
**h. \( (x - 1)(x^2 + x + 1) \) :**
\[ x \cdot (x^2 + x + 1) - 1 \cdot (x^2 + x + 1) \]
\[ x^3 + x^2 + x - x^2 - x - 1 \]
\[ x^3 - 1 \]
**i. \(2 - (x + 3)(2x + 1)\) :**
\[ 2 - (x \cdot 2x + x \cdot 1 + 3 \cdot 2x + 3 \cdot 1) \]
\[ 2 - (2x^2 + x + 6x + 3) \]
\[ 2 - 2x^2 - 7x - 3 \]
