Question 9 Simplify the expression completely (Make sure no negative exponents are included.) \( \left(9 z^{-12}\right)\left(6 z^{7}\right)=\square \)

To simplify the expression \( \left(9 z^{-12}\right)\left(6 z^{7}\right) \), start by multiplying the coefficients and adding the exponents of the same base. So, first calculate the coefficients: \( 9 \times 6 = 54 \). Next, for the variable part, add the exponents: \[ -12 + 7 = -5. \] This gives you: \[ 54 z^{-5}. \] To eliminate the negative exponent, rewrite it as: \[ \frac{54}{z^{5}}. \] So, the final simplified expression is \[ \frac{54}{z^{5}}. \]