Show that m^2-8m+12=0

x^2+(m+4)x+4m+1)=0, where m is a constant, has equal roots.
show that m^2-8m+12=0

please show the working out if possible :) thank you

m² - 4m = - 12 + 4²
m² - 4m = - 12 + 16
(m - 4)² = 4
m - 4 = ± 2

m = 4 - 2, m = 2
m = 4 + 2, m = 6

Proof:
= 2² - 8(2) + 12
= 4 - 16 + 12
= 0

= 6² - 8(6) + 12
= 36 - 48 + 12
= 0

Answer: proof as indicated above.