Given that x^2-5x=0, to solve it using the complete square method, we need the value of c. The quadratic equation is in the form of :
ax^2+bx+c=0
to get c we use the formula:
c=(b/2a)^2
b=-5
a=1
thus
c=(-5/2*1)^2
c=25/4
the number that should be added is 25/4