To find the product of the polynomials \((2x + 1)(x - 4)\), we will use the distributive property (also known as the FOIL method for binomials).
Let's distribute each term in the first polynomial by each term in the second polynomial:
\[ (2x + 1)(x - 4) = 2x \cdot x + 2x \cdot (-4) + 1 \cdot x + 1 \cdot (-4) \]
Now, let's perform the calculations for each term:
- \(2x \cdot x = 2x^2\)
- \(2x \cdot (-4) = -8x\)
- \(1 \cdot x = x\)
- \(1 \cdot (-4) = -4\)
Now, combine all these terms:
\[ 2x^2 - 8x + x - 4 \]
Now, combine like terms:
\[ 2x^2 + (-8x + x) - 4 = 2x^2 - 7x - 4 \]
Thus, the product of the polynomials \((2x + 1)(x - 4)\) is:
\[ \boxed{2x^2 - 7x - 4} \]