Answer
$a^2+5a-24$.
Work Step by Step
The given expression is
$=(a+8)(a-3)$
Distribute $(a-3)$ to each term of $(a+8)$.
$=a(a-3)+8(a-3)$
Use distributive property.
$=a(a)+a(-3)+8(a)+8(-3)$
Multiply.
$=a^2-3a+8a-24$
Combine like terms.
$=a^2+5a-24$
Hence, the product is $a^2+5a-24$.
