Question

3a³-81

Answer 1

\(3a^3-81\)

\(=3\left(a^3-27\right)\)

\(=3\left(a^3-3^3\right)\)

\(=3\left[\left(a-3\right)\left(a^2+a.3+3^2\right)\right]\)

\(=3\left(a-3\right)\left(a^2+a.3+9\right)\)

Answer 2

\(3a^3-81\)

\(=3.\left(a^3-27\right)\)

\(=3.\left(a^3-3^3\right)\)

\(=3.\left[\left(a-3\right).\left(a^2+3.a+3^2\right)\right]\)

\(=3.\left(a-3\right).\left(a^2+3a+9\right)\)

Chúc bạn học tốt!