a: \(-2x^2y\left(\frac32xy^2-5xy+\frac13x^2y^2\right)\)
\(=-2x^2y\cdot\frac32xy^2+2x^2y\cdot5xy-2x^2y\cdot\frac13x^2y^2\)
\(=-3x^3y^3+10x^3y^2-\frac23x^4y^3\)
b: \(\frac34x\left(x^2-25\right)=0\)
=>x(x-5)(x+5)=0
=>\(\left[\begin{array}{l}x=0\\ x-5=0\\ x+5=0\end{array}\right.\Rightarrow\left[\begin{array}{l}x=0\\ x=5\\ x=-5\end{array}\right.\)

