How do you solve # x^2-4x-7=0#?
The given equation does not factorise, so option 1 falls away.
My choice would be completing the square because:
the coefficient of
Student often think completing the square is difficult, but in a case like this it is quicker and easier than using the formula.
Move the constant to the RHS:
Add on the square of, half of the middle coefficient to both sides:
The LHS is now the square of a binomial