Respuesta :

If you complete the square you get

[tex]{(x - 4) }^{2} + 4[/tex]

and as any number squared is positive and 4 is positive, the result must be positive

Answer:

x^2-8x+20=x^2-2*x*4+4^2+4=(x-4)^2+4

so (x-4)^2 is positive or zero (but +4  is always positive)

Step-by-step explanation: