SOLUTION:
Simplify;
[tex]-4u^2(-5u^3)[/tex]
Using product rule;
[tex](-\times-)(4\times5)(u^2\times u^3)[/tex]
From Indices law;
[tex]a^b\times a^c=a^{b+c}[/tex]
Thus;
[tex]\begin{gathered} (-\operatorname{\times}-)(4\times5)(u^2\times u^3)=(+)(20)(u^{2+3}) \\ =20u^5 \end{gathered}[/tex]
FINAL ANSWER:
[tex]\begin{equation*} 20u^5 \end{equation*}[/tex]
