Question

(x+y) • (x+y) • ( x+y)

Answer 1

(x+y)(x+y)
x² + xy + xy + y²
x² + 2xy + y²

(x² + 2xy + y²)(x+y)
x³ + x²y + 2x²y + 2xy² + xy² + y³
x³ + 3x²y + 3xy² + y³