Respuesta :

to complete the square, notice (x + a)^2 = x^2 + 2ax + a^2

so here 2a = -8

a = -4

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

C = 16
Expression: x² - 8x + c

Compare it with the the principle form, ax + bx + c = 0

Here, b = -8

We know,  c= -2b = -2(-8) = 16

In short, Your Answer would be: 16

Hope this helps!