Cho biểu thức (a + b)^n , với n = 4 ta có khai triển là A. (a + b)^4 =

(a + b)⁴ = \(C_4^0{a^4} + C_4^1{a^3}{b^1} + C_4^2{a^2}{b^2} + C_4^3a{b^3} + C_4^4{b^4}\);

(a + b)⁴ = \(C_4^0{a^4} - C_4^1{a^3}{b^1} - C_4^2{a^2}{b^2} - C_4^3a{b^3} - C_4^4{b^4}\);

(a + b)⁴ = \(C_4^0{a^4} - C_4^1{a^3}{b^1} + C_4^2{a^2}{b^2} - C_4^3a{b^3} + C_4^4{b^4}\);

(a + b)⁴ = \( - C_4^0{a^4} - C_4^1{a^3}{b^1} - C_4^2{a^2}{b^2} - C_4^3a{b^3} - C_4^4{b^4}\).