8.
已知函数\(f(x)=\log _{2}x\),函数\(g(x)=3-2\log _{2}x.\)
\((1)\)若函数\(F(x)=[g(x)]^{2}-λf(x),x∈[ \dfrac {1}{8},+∞)\)的最小值为\(-16\),求实数\(λ\)的值;
\((2)\)当\(x∈[ \dfrac {1}{8},2]\)时,不等式\(2^{3-g( \sqrt {x})}-2^{f(x^{2})}\leqslant \ln T\)的解集为\(\varnothing \),求实数\(T\)的取值范围.