To multiply the expressions \((x+1)(x+3)\), you can use the distributive property (often called the FOIL method for binomials).
Here's how it works step by step:
-
First, multiply the first terms:
\(x \cdot x = x^2\) -
Next, multiply the outer terms:
\(x \cdot 3 = 3x\) -
Then, multiply the inner terms:
\(1 \cdot x = x\) -
Finally, multiply the last terms:
\(1 \cdot 3 = 3\)
Now, combine all these results together:
\[
x^2 + 3x + x + 3
\]
Combine like terms (the \(3x\) and \(x\)):
\[
x^2 + 4x + 3
\]
So, \((x+1)(x+3)\) simplifies to:
\[
\boxed{x^2 + 4x + 3}
\]