Question

Multiply:

(9) (x + 2y) (x² − 2xy + 4y²)

Answer 1

(x + 2y) (x² − 2xy + 4y²)
= x(x² − 2xy + 4y²) + 2y(x² − 2xy + 4y²)
= (x × x²) − (x × 2xy) + (x × 4y²) + (2y × x²) - (2y × 2xy) + (2y × 4y²)
= x³ − 2x²y + 4xy² + 2x²y − 4xy² + 8y³
= x³ + (−2x²y + 2x²y) + (4xy² − 4xy²) + 8y³
= x³ + 0 + 0 + 8y³
= x³ + 8y³