\(\frac{1}{27}+x^3\)
\(=\left(\frac{1}{3}\right)^3+x^3\)
\(=\left(\frac{1}{3}+x\right)\left(\frac{1}{9}-\frac{1}{3}x+x^2\right)\)
\(\frac{1}{27}+x^3=\left(\frac{1}{3}\right)^3+x^3\)\(\left(\frac{1}{3}+x\right)\left[\left(\frac{1}{3}\right)^2-\frac{1}{3}x+x^2\right]\)