Evaluate the expression when \( x=3 \) and \( z=9 \). Simplify your answer completely. \[ 4 x^{3}+\pi \]

To evaluate the expression \( 4 x^{3} + \pi \) when \( x = 3 \), we start by substituting \( x \) with 3: \[ 4(3)^{3} + \pi \] Now, calculate \( (3)^{3} \), which is \( 27 \): \[ 4 \cdot 27 + \pi \] Now multiply \( 4 \) and \( 27 \): \[ 108 + \pi \] Thus, the expression simplifies to: \[ 108 + \pi \] So, when \( x = 3 \), the evaluated expression is \( 108 + \pi \).