Step-by-step explanation:
First take out the highest common factor of which is: -2x(the reason we make the common factor negative is because we want to make the coefficient of x^2 positive so that the factorising can be easier)
And then we find common factors of 6 and the coefficient of the squared variable that add up to -1 of which is two and three.
*Note: if the sign between the variable and the 6 is the same then the largest bracket gets a positive sign