What Must Be Added To x^2 + 10x + 23 To Make It A Perfect Square

Answer 1

write
x^2 + 10 x
add half of ten squared
5^2 = 25
so
x^2 + 10 x + 25 is a perfect square
so we need to add 2
to 23
to make 25

and then
(x+5)^2 = x^2 + 10 x + 25