What is the value of $(a + b)^3 - a^3 - b^3 $ ?

3ab (a - b) -3ab(a - b) 3ab ( a + b) -3ab ( a + b)

3ab ( a + b)

$(a + b)^3 - a^3 - b^3 $ = a3 + b3 + 3ab(a+b)  - $a^3 - b^3 $  = 3ab ( a + b)