Question

Which of the following is the correct expansion of (y + 1)(y2 + 2y + 3)?

Answer 1

Use distributive property:

(a + b)(c + d) = ac + ad + bc + bd

(y + 1)(y² + 2y + 3) = (y)(y²) + (y)(2y) + (y)(3) + (1)(y²) + (1)(2y) + (1)(3)

= y³ + 2y² + 3y + y² + 2y + 3 = y³ + (2y² + y²) + (3y + 2y) + 3

= y³ + 3y² + 5y + 3