b) \(\frac{2}{3}x^3y^4-\frac{5}{3}x^5y^2\)
\(=x^3y^2\left(\frac{2}{3}y^2-\frac{5}{3}x^2\right)\)
\(=x^3y^2\left(\sqrt{\frac{2}{3}}y+\sqrt{\frac{5}{3}}x\right)\left(\sqrt{\frac{2}{3}}y-\sqrt{\frac{5}{3}}x\right)\)
d) \(x^2-25=\left(x+5\right)\left(x-5\right)\)