9.
\((1)\) 如果根式\(\sqrt{x{+}1}\)有意义,则\(x\)的取值范围是_________.
\((2)\) 某种油菜籽在相同条件下的发芽试验结果如下:
每批粒数\(n\) | \(0\) | \(400\) | \(800\) | \(00\) | \(2000\) | \(4000\) |
发芽的频数\(m\) | \(85\) | \(300\) | \(652\) | \(793\) | \(1604\) | \(3204\) |
发芽的频率 | \(0{.}850\) | \(0{.}750\) | \(0{.}815\) | \(0{.}793\) | \(0{.}802\) | \(0{.}801\) |
由此可以估计油菜籽发芽的概率约为_____________\({.}(\)精确到\(0{.}1)\)
\((3)\) 若分式\(\dfrac{{x}^{2}-9}{x+3} \)的值为零,则\(x{=}\)____________.
\((4)\) 若\(a\)、\(b\)为实数满足\(\left| a{-}2 \right|{+}\sqrt{b{+}1}{=}0\),则\(a{+}b\)的值为________________.
\((5)\)已知\(\dfrac{2}{a}{=}\dfrac{1}{b}\),则\(\dfrac{2a{+}b}{a{-}b}\)的值是______ .
\((6)\)如图,在矩形\(ABCD\)中,\(E\)为\(BC\)中点,作\({∠}AEC\)的角平分线交\(AD\)于\(F\)点\({.}\)若\(AB{=}3\),\(AD{=}8\),则\(FD\)的长为____________.
\((7)\)如图,在\({\triangle }ABC\)中,\(AC{=}8\),\(BC{=}10\),\(F\)是中位线\(DE\)所在直线上一动点,当\({∠}AFC{=}90^{{∘}}\)时,\(DF\)的长度为______________.
\((8)\)如图,正方形\(ABCD\)的边长为\(5\),\(AE{=}CF{=}4\),\(BE{=}DF{=}3\),连接\(EF\),则线段\(EF\)的长为______________.