(5a + 4b)² - (5 - 4b)²= (5a + 4b)(5a + 4b) - (5 - 4b)(5 - 4b)= 25a² + 20ab + 16b² - (25 - 40b + 16b²)= 25a² + 20ab + 16b² - 25 + 40b - 16b²= 25a² + 20ab + 16b² - 25 + 40b - 16b²= 25a² + 20ab + 40b - 25
(10p - 3q)² + (5p + 6)²= (10p - 3q)(10p - 3q) + (5p + 6)(5p + 6)= 100p² - 60pq + 9q² + 25p² + 60p + 36= 125p² - 60pq + 9q² + 60p + 36
t(9t - 1)² - 81t(t - 4)²= t(81t² - 18t + 1) - 81t(t² - 8t + 16)= 81t³ - 18t² + t - 81t³ + 648t² - 1296t= 648t² - 18t² + 648t - 1296t
5mn - 2(3m - n)² + 9m²= 5mn - 2(9m² - 6mn + n²) + 9m²= 5mn - 18m² + 12mn - 2n² + 9m²= -9m² + 17mn - 2n²
(5a + 4b)² - (5 - 4b)²
= (5a + 4b)(5a + 4b) - (5 - 4b)(5 - 4b)
= 25a² + 20ab + 16b² - (25 - 40b + 16b²)
= 25a² + 20ab + 16b² - 25 + 40b - 16b²
= 25a² + 20ab + 16b² - 25 + 40b - 16b²
= 25a² + 20ab + 40b - 25
(10p - 3q)² + (5p + 6)²
= (10p - 3q)(10p - 3q) + (5p + 6)(5p + 6)
= 100p² - 60pq + 9q² + 25p² + 60p + 36
= 125p² - 60pq + 9q² + 60p + 36
t(9t - 1)² - 81t(t - 4)²
= t(81t² - 18t + 1) - 81t(t² - 8t + 16)
= 81t³ - 18t² + t - 81t³ + 648t² - 1296t
= 648t² - 18t² + 648t - 1296t
5mn - 2(3m - n)² + 9m²
= 5mn - 2(9m² - 6mn + n²) + 9m²
= 5mn - 18m² + 12mn - 2n² + 9m²
= -9m² + 17mn - 2n²