a + b = 9 a * b = - 12
(a + b)² = 9²
a² + 2ab + b² = 81
a² + b² = 81 - 2ab = 81 - 2 * (- 12) = 81 + 24 = 105
a² + b² = 105
(a - b)² = a² - 2ab + b² = (a² + b²) - 2ab = 105 - 2 * (- 12) = 105 + 24 = 129
(a - b)² = 129
a + b = 9 a * b = - 12
(a + b)² = 9²
a² + 2ab + b² = 81
a² + b² = 81 - 2ab = 81 - 2 * (- 12) = 81 + 24 = 105
a² + b² = 105
(a - b)² = a² - 2ab + b² = (a² + b²) - 2ab = 105 - 2 * (- 12) = 105 + 24 = 129
(a - b)² = 129