you use the quadratic formula -b +/- and then underneath the root thing -b^2- 4ac and then all over 2a and then plug in so a=1 b=-4 c=4. So it would look like this: -(-4)+/- and then underneath the root thing -4^2 -4(1)(4) and all over 2(1). Then 4+/- and underneath the root thing 16 -16 and all over 2