Here is a scaffolded handout. The first problem has additional scaffolding to convert from addition to subtraction and vise versa. The first problem does not require the transformation of the operations but the second one does.
Completing the Square – Scaffolded Handout
Here is a link to a scaffolded handout with all the steps, including the step to convert the lead coefficient to 1. The scaffolding is complex because the math topic is complex. There is an example showing how to use the document.