6.
\((1)\)与直线\(2x-y+4=0\)平行的抛物线\(y={{x}^{2}}\)的切线方程是
\((2)\)若复数\(z\)满足\((3+4\)\(i\)\()\)\(z\)\(=|3-4\)\(i\)\(|\),其中\(i\)为虚数单位,则\(z\)虚部为
\((3)\)若函数\(f\)\((\)\(x\)\()=\)\(x\)\({\,\!}^{3}-3\)\(x\)在\((\)\(a\),\(6-\)\(a\)\({\,\!}^{2})\)上有最大值,则实数\(a\)的取值范围是
\((4)\)已知函数\(f\)\((\)\(x\)\()=\ln \) \(x\)\(- \dfrac{1}{4} \) \(x\)\(+ \dfrac{3}{4x} -1\),\(g\)\((\)\(x\)\()=-\)\(x\)\({\,\!}^{2}+2\)\(bx\)\(-4\),若对任意的\(x\)\({\,\!}_{1}∈(0,2)\),任意的\(x\)\({\,\!}_{2}∈[1,2]\),不等式\(f\)\((\)\(x\)\({\,\!}_{1})\geqslant \)\(g\)\((\)\(x\)\({\,\!}_{2})\)恒成立,则实数\(b\)的取值范围是