For this case we have that by definition, the distributive property establishes that:
![(a + b) (c + d) = ac + ad + bc + bd](https://img.qammunity.org/2020/formulas/mathematics/high-school/niqhmylmiq7kdq4gdnhr7nkwta2fgqw8xz.png)
If we have two polynomials of the form:
![P (x) = ax ^ 2 + x\\G (x) = x + 3](https://img.qammunity.org/2020/formulas/mathematics/middle-school/dq685ngj3yuiz31giqlgqtbtyzxul2hklq.png)
To multiply we apply the definition of distributive property, having that to multiply powers of the same base, the same base is placed and the exponents are added.
![P (x) * g (x) = (ax ^ 2 + x) (x + 3) = ax ^ 3 + 3ax ^ 2 + x ^ 2 + 3x](https://img.qammunity.org/2020/formulas/mathematics/middle-school/sd38p2y9bfd5mjw2lzkrbeff1lnj0wclu0.png)
Answer:
![(a + b) (c + d) = ac + ad + bc + bd](https://img.qammunity.org/2020/formulas/mathematics/high-school/niqhmylmiq7kdq4gdnhr7nkwta2fgqw8xz.png)