4x(x-5)

To simplify the expression \(4x(x - 5)\), you can distribute \(4x\) to both terms inside the parentheses:

\[ 4x(x - 5) = 4x \cdot x - 4x \cdot 5 \]

This results in:

\[ 4x^2 - 20x \]

So, the simplified form of the expression \(4x(x - 5)\) is:

\[ 4x^2 - 20x \]