a: \(\sqrt[3]{27}-\sqrt[3]{-8}+\frac15\cdot\sqrt[3]{-125}\)
\(=3-\left(-2\right)+\frac15\cdot\left(-5\right)\)
=3+2-1
=5-1
=4
b: \(\sqrt[3]{\frac{125}{512}}+\sqrt[3]{125}-\frac13\cdot\sqrt{27}\)
\(=\frac58+5-\frac13\cdot3\sqrt3=\frac{45}{8}-\sqrt3\)
c: \(\sqrt[3]{x^3+3x^2+3x+1}\)
\(=\sqrt[3]{\left(x+1\right)^3}\)
=x+1
d: \(\sqrt[3]{8x^3+12x^2+6x+1}\)
\(=\sqrt[3]{\left.\left(2x+1\right)^3\right.}\)
=2x+1

