For context I'm taking a math class for the first time in 6 years so there's quite a few things I've forgotten about. If there's any errors in my post please feel free to correct me.

Now regarding the the complete the square method I have a general understanding of it. However the part I'm a bit confused about is when I should use this method. I know the quadratic formula is derived from complete the square and typically it's used when a quadratic equation can't be easily factored. So when I come across a quadratic equation that can't be factored how do I know if I should use complete the square instead of the quadratic formula and vice versa?