\(=\left(x^2-x+1\right)^2+\left(x^2-x+1\right)-20\\ =\left(x^2-x+1\right)^2-4\left(x^2-x+1\right)+5\left(x^2-x+1\right)-20\\ =\left(x^2-x+1\right)\left(x^2-x+1-4\right)+5\left(x^2-x+1-4\right)\\ =\left(x^2-x+1-4\right)\left(x^2-x+1+5\right)\\ =\left(x^2-x-3\right)\left(x^2-x+6\right)\\ =\left(x-3\right)\left(x+2\right)\left(x^2-x-3\right)\)