a: \(=3\left[\left(m-5\right)^3+8\right]\)
\(=3\left(m-5+2\right)\left[\left(m-5\right)^2-2\left(m-5\right)+4\right]\)
\(=3\left(m-3\right)\left(m^2-10m+25-2m+10+4\right)\)
\(=3\left(m-3\right)\left(m^2-12m+39\right)\)
b: \(=5\left(1-6k\right)^3-5\cdot64\)
\(=5\left(1-6k-4\right)\left[\left(1-6k\right)^2+4\left(1-6k\right)+16\right]\)
\(=5\left(-6k-3\right)\left(36k^2-12k+1+4-24k+16\right)\)
\(=-15\left(2k+1\right)\left(36k^2-36k+21\right)\)
\(=-45\left(2k+1\right)\left(12k^2-12k+7\right)\)
c: \(=\left(a+b-2b+a\right)\left[\left(a+b\right)^2+\left(a+b\right)\left(2b-a\right)+\left(2b-a\right)^2\right]\)
\(=\left(2a-b\right)\left(a^2+2ab+b^2+2ab-a^2+2b^2-ab+4b^2-4ab+b^2\right)\)
\(=\left(2a-b\right)\cdot b\cdot\left(6b+a\right)\)