If using the method of completing the square to solve the quadratic equation x^2-2x-1=0x 2 −2x−1=0, which number would have to be added to "complete the square"

Acd that is originally priced at $15.85 red-tagged for the sale. what is the sale price of the cd

Avery’s piggy bank has 300 nickels, 450 pennies, and 150 dimes. she randomly picks three coins. each time she picks a coin, she makes a note of it and puts it back into the piggy bank before picking the next coin.

If set d is not the empty set but is a subset of set e, then which of the following is true? d ∩ e = d d ∩ e = e d ∩ e = ∅