Explications étape par étape:
1.,(2x - 7)(4x + 3)
<=> 2x × 4x + 2x × 3 - 7 × 4x - 7 × 3
<=> 8x² + 6x - 28x - 21
<=> 8x² - 22x - 21
2. (3a + 8)(2a + 2)
<=> 3a × 2a + 3a × 2 + 8 × 2a + 8 × 2
<=> 6a² + 6a + 16a + 16
<=> 6a² + 22a + 16
3. (7 - 5t)(-8 + 3t)
<=> 7 × (-8) + 7 × 3t - 5t × (-8) - 5t × 3t
<=> -56 + 21t + 40t - 15t²
<=> -15t² + 61t - 56
