b: \(x^6-1\)
\(=\left(x^3-1\right)\left(x^3+1\right)\)
\(=\left(x-1\right)\left(x+1\right)\left(x^2+x+1\right)\left(x^2-x+1\right)\)
c: \(3x^2+5x-3y^2-5y\)
\(=\left(3x^2-3y^2\right)+\left(5x-5y\right)\)
\(=3\left(x-y\right)\left(x+y\right)+5\left(x-y\right)\)
\(=\left(x-y\right)\left(3x+3y+5\right)\)