(a+5)² = (a+5)*(a+5) = a² + 5a +5a + 25 = a² + 10a + 25
(4-3b)² = (4-3b)*(4-3b) = 16 -12b - 12b +9b² = 16 -24b +9b²
(a+b+c)² = (a+b+c)*(a+b+c) = a² + ab + ac + ab + b² + bc + ac + bc + c² =
= a² + b² + c² + 2ab + 2ac + 2bc
(a-b)³ = (a-b)*(a-b)*(a-b) = (a² - 2ab + b²)*(a - b) =
= a³ - a²b - 2a²b + 2ab² + ab² - b³ = a³ - 3a²b + 3ab² - b³