Question

(x+3y) (x^2-3xy+9y^2)

Answer 1

$(x + 3y)( {x}^{2} - 3xy + 9 {y}^{2} ) \\ x( {x}^{2} - 3xy + 9 {y}^{2} ) + 3y( {x}^{2} - 3xy + 9 {y}^{2} ) \\ {x}^{3} - 3 {x}^{2} y + 9x {y}^{2} + 3 {x}^{2} y - 9x {y}^{2} + 27y ^{3} \\ {x}^{3} + 27 {y}^{3}$