Question

find the maximum or minimum value 12

Answer 1

for max. and min., you need to rewrite the equation in the form of
y = a(x-h)^2 +k
where k gives you the max(+ve)/ min (-ve) value
x=h is the axis of symmetry

Answer 2

f(x)=x^2-2x-8
f'=2x-2
2x-2=0
x=1

Answer 3

(1,-9)