Problem
$f(x)=(2 x+1)(x+4)$
Solution
Step 1 ：Given the function \(f(x)=(2 x+1)(x+4)\).
Step 2 ：This is a multiplication of two binomials. To solve this, we can use the distributive property to multiply each term in the first binomial with each term in the second binomial.
Step 3 ：Applying the distributive property, we get \(f(x) = 2x^2 + 9x + 4\).
Step 4 ：Final Answer: \(f(x) = \boxed{2x^2 + 9x + 4}\)
