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

y3 + 3y2 + 5y + 3

y3 + y2 + y + 3

y3 + 6y2 + 5y + 9

y3 + 5y2 + 6y + 3

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