(-20 x²y^6z) *(2,5x^5y³z⁴)

To multiply the two expressions \((-20 x^2y^6z)\) and \((2.5 x^5y^3z^4)\), you can follow these steps:

1. Multiply the coefficients: \[ -20 \times 2.5 = -50 \]

2. Multiply the variables:

   • For \(x\): \[ x^2 \times x^5 = x^{2+5} = x^7 \]
   • For \(y\): \[ y^6 \times y^3 = y^{6+3} = y^9 \]
   • For \(z\): \[ z \times z^4 = z^{1+4} = z^5 \]

Putting it all together, we have:

\[ (-20 x^2 y^6 z) \times (2.5 x^5 y^3 z^4) = -50 x^7 y^9 z^5 \]

So, the final answer is:

\[ \boxed{-50 x^7 y^9 z^5} \]