what value of k makes the given expression a perfect square?M square -8m+k

2 answers

m^2 - 8 m + k

(m-x)(m-x) = m^2 -2 x m + x^2
so
2 x = -8
x = -4
x^2 = 16 = k
so
m^2 - 8 m + 16

in general to complete the square
1 x^2 + b x + c
if that is to be a perfect square
c = (b/2)^2
my question is what is the value of k that makes the given expression a perfect square 2m²-8m+k