Fill in the blanks with integers to get an identity.
(n - k + 2)^2 = __ n^2 + ___ k^2 + ___ n + ___k + ___ nk + ___
Use the identity (a+b+c)2=a2+b2+c2+2ab+2bc+2ca.
(n−k+2)2=1n2+1k2+4n+(−4)k+(−2)nk+4.
+821 
