Question

(a + b)³-(a - b)³- 6a²b

Answer 1

Step-by-step explanation:

$(a + b)^{3} - (a - b)^{3} - 6 {a}^{2} b \\ a ^{3} + 3a ^{2} b + 3ab ^{2} + b ^{3} - (a ^{3} - 3a ^{2} b + 3ab ^{2} - b ^{3}) - 6 {a}^{2} b \\ a ^{3} + 3a ^{2} b + 3ab ^{2} + b ^{3} - a ^{3} + 3a ^{2} b - 3ab ^{2} + b ^{3}) - 6 {a}^{2} b \\ 3a ^{2} b + b ^{3} + 3a ^{2} b + b ^{3} - 6 {a}^{2} b \\ 6 {a}^{2} b + 2b ^{3} - 6 {a}^{2} b \\ 2b ^{3}$

Answer 2

Answer:

2b^3

Step-by-step explanation:

$(a+b)^3=a^3+b^3+3ab(a+b)\\(a-b)^3=a^3-b^3-3ab(a-b)\\(a+b)^3-(a-b)^3-6a^2b\\=a^3+b^3+3ab(a+b)-[a^3-b^3-3ab(a-b)]-6a^2b\\=2b^3$