Select the correct product. (y + z)3 y3 + z3 y3 + 3y2z + 3yz2 + z3 3y + 3z y3z3

(y + z)³         ( i believe you were trying to do the expression to the power of 3)

(y + z)³ = (y + z)(y + z)(y + z)

Use the FOIL method:
(y + z)(y + z) = y² + yz + yz + z²
Simplify
y² + 2yz + z²

plug in the answer gotten back into the expression

(y² + 2yz + z²)(y + z)

FOIL again, distribute each number to the other.

y²(y) = y³
y(2yz) = 2y²z
y(z²) = yz²
y²(z) = y²z
2yz(z) = 2yz²
z(z²) = z³

2y²z + 2yz² + y³ + z³ + y²z + yz² 

Simplify: add all like variables

2y²z + y²z = 3y²z
2yz² + yz² = 3yz²

3y²z + 3yz² + y³ + z³ is your answer, or y^3 + 3y^2z + 3yz^2 + z^3

hope this helps