Answer:
100.
Step-by-step explanation:
[tex] x(x+8) = 9[/tex]
[tex] x^2+8x = 9[/tex]
[tex] x^2+8x-9 = 0[/tex]
In that formula we have that a = 1 (coefficient of x^2), b = 8 (coefficient of x) and c= -9 (independent term). Then,
[tex]b^2-4ac = 8^2-4(1)(-9) = 64+36 = 100[/tex].
