Please explain the sum very clearly clearly

If b^2-4ac=0 then show ax^2 plus bx plus c is a perfect square

If b^2-4ac = 0 then b^2 = 4ac.
We can then write ax^2 + bx + c as ax^2 +- 2 sqrt(ac) + c, which can also be written as
( sqrt(a)+-sqrt(b) )^2, which is a perfect square.

ax^2 + bx + c
let a=m^2,c=n^2
(mx)^2 + bx + n^2

(mx+n)^2= (mx)^2+2*mx*n+n^2

if b={(2*mx*n)/x}=2*m*n
b^2=4*m^2*n^2=4ac

this math question is really SUMtim