Question

$f(x)= sqrt{(1/3)}^{2x-9} -9$

Answer 1

$(1/3) ^{2x-9} -9 geq 0$
$(1/3) ^{2x-9 } geq (1/3) ^{-2}$
2x-9≤-2
2x≤7
x≤3,5
x∈(-∞;3,5]
x=3