一 、 單 選 題 ( 占 3 0 分)
1. 請問下列哪一個選項等於 \(log(2^{(3^{5})})\)
(1) \(5\, log\left ( 2^{3} \right )\)
(2) \(3\times5\, log\, 2\)
(3) \(5\, log\, 2\times log\, 3\)
(4) \(5\left ( log\, 2+log\, 3 \right )\)
(5) \(3^{5}\, log\, 2\)
如果底數 a 為10可省略不寫:
\(log{_{10}}^{b^{c}}=log\left ( b^{c} \right )=c\, log\, b\)
A: (5)
2. 令 \(A(5,0,12)\)、\(B(-5,0,12)\) 為坐標空間中之兩點,且令 \(P\) 為 \(xy\) 平面上滿足 \(\overline{PA}=\overline{PB}=13\) 的點。請問下列哪一個選項中的點可能為 \(P\) ?
(1) \((5,0,0)\)
(2) \((5,5,0)\)
(3) \((0,12,0)\)
(4) \((0,0,0)\)
(5) \((0,0,24)\)
所以第(5)個選項 \((0,0,{\color{Red} 24})\) 當然是錯的啦
\(\overline{QA}=\left | \overrightarrow{QA} \right |=\left | (5-5,0-0,12-0) \right |=\left | (0,0,12) \right |={\color{Red} 12}\)
\(\overline{QA}\neq 13\) 由此可見(1)是錯的
\(\overline{OA}=\left | \overrightarrow{OA} \right |=\left | (5-0,0-0,12-0) \right |=\left | (5,0,12) \right |=\sqrt{5^{2}+0^{2}+12^{2}}={\color{Green} 13}\)
\(\overline{OA}=13\) 由此可見 \(O\) 點有可能為\(P\) 點
A: (4)
3. 在坐標平面上, 以 \(\left ( 1,1 \right )\), \(\left ( -1,1 \right )\), \(\left ( -1,-1 \right )\) 及 \(\left ( 1,-1 \right )\) 等四個點為頂點的正方形, 與圓 \(x^{2}+y^{2}+2x+2y+1=0\) 有幾個交點?
(1) 1 個
(2) 2 個
(2) 3 個
(2) 4 個
(2) 0 個
將圓C: \(x^{2}+y^{2}+2x+2y+1=0 \; \;\)標準化
將圓C: \(x^{2}+y^{2}+2x+2y+1=0\; \; \)標準化
\(\Rightarrow \;\; x^{2}+2x+1+y^{2}+2y=0\)
\(\Rightarrow \;\; x^{2}+2x+1+y^{2}+2y{\color{Green} \:\: +1}=0{\color{Green} \: +1}\)
\(\Rightarrow \; \; \left ( x+1 \right )^{2}+\left ( y+1 \right )^{2}=1\)
可看出圓C的圓心坐標為\({\color{Red} \left ( -1,-1 \right )}\), 半徑\({\color{Red} r=1}\)
由圖可知圓與正方形交於兩點
4. 請問滿足絕對值不等式\(\, \left | 4x-12 \right |\leq 2x\,\)的實數\(\, x\,\)所形成的區間, 其長度為下列哪一個選項?
(1) 1
(2) 2
(3) 3
(4) 4
(5) 6
\(\, \left | 4x-12 \right |\leq 2x\,\)
\(\Rightarrow \, \; \; {\color{Green} 2}\left | 2x-6 \right |\leq{\color{Green} 2}x\) \(\Rightarrow \, \; \; \left | 2x-6 \right |\leq x\)
\(\, \left | 4x-12 \right |\leq 2x\,\)
\(\Rightarrow \, \; \; {\color{Green} 2}\left | 2x-6 \right |\leq{\color{Green} 2}x\) \(\Rightarrow \, \; \; \left | 2x-6 \right |\leq x\)
因絕對值\(\, \left | 2x-6 \right |\,\)恆\(\, \geq 0\,\) , 且\(\, \left | 2x-6 \right |\leq x\)
故\(\, {\color{Red} x\geq 0}\)
兩邊平方後不等式仍然成立
\(\Rightarrow \; \; \left ( 2x-6 \right )^{{\color{Green} 2}}\leq x^{{\color{Green} 2}}\)
兩邊平方後不等式仍然成立
\(\Rightarrow \; \; \left ( 2x-6 \right )^{{\color{Green} 2}}\leq x^{{\color{Green} 2}}\) \(\Rightarrow \; \; 4x^{2}-24x+36\leq x^{2}\)
\(\Rightarrow \; 3x^{2}-24x+36\leq 0\) \(\Rightarrow \; x^{2}-8x+12\leq 0\)
兩邊平方後不等式仍然成立
\(\Rightarrow \; \; \left ( 2x-6 \right )^{{\color{Green} 2}}\leq x^{{\color{Green} 2}}\) \(\Rightarrow \; \; 4x^{2}-24x+36\leq x^{2}\)
\(\Rightarrow \; 3x^{2}-24x+36\leq 0\) \(\Rightarrow \; x^{2}-8x+12\leq 0\)
因式分解 \(\Rightarrow \; \left ( x-2 \right )\left ( x-6 \right )\leq 0\)
兩邊平方後不等式仍然成立
\(\Rightarrow \; \; \left ( 2x-6 \right )^{{\color{Green} 2}}\leq x^{{\color{Green} 2}}\) \(\Rightarrow \; \; 4x^{2}-24x+36\leq x^{2}\)
\(\Rightarrow \; 3x^{2}-24x+36\leq 0\) \(\Rightarrow \; x^{2}-8x+12\leq 0\)
因式分解 \(\Rightarrow \; \left ( x-2 \right )\left ( x-6 \right )\leq 0\)
你能找出不等式 \(\left ( x-2 \right )\left ( x-6 \right )\leq 0\)的解區間嗎?
你知道這是什麼圖形嗎?
沒錯, 開口向上的拋物線,
與x軸交於2, 6
現在你能找出不等式
\(\left ( x-2 \right )\left ( x-6 \right )\leq 0\)
的解區間嗎?
不等式
\(\left ( x-2 \right )\left ( x-6 \right )\leq 0\)
的解區間為
\(2\leq x\leq 6\)
長度為4
5. 設\(\; \left ( 1+\sqrt{2} \right )^{6}=a+b\sqrt{2}\;\), 其中a,b 為整數。請問b 等於下列哪一個選項?
(1) \(C_{\, 0}^{\, 6}+2\, C_{\, 2}^{\, 6}+2^{2}\, C_{\, 4}^{\, 6}+2^{3}\, C_{\, 6}^{\, 6}\)
(2) \(C_{\, 1}^{\, 6}+2\, C_{\, 3}^{\, 6}+2^{2}\, C_{\, 5}^{\, 6}\)
(3) \(C_{\, 0}^{\, 6}+2\, C_{\, 1}^{\, 6}+2^{2}\, C_{\, 2}^{\, 6}+2^{3}\, C_{\, 3}^{\, 6}+2^{4}\, C_{\, 4}^{\, 6}+2^{5}\, C_{\, 5}^{\, 6}+2^{6}\, C_{\, 6}^{\, 6}\)
(4) \(2\, C_{\, 1}^{\, 6}+2^{2}\, C_{\, 3}^{\, 6}+2^{3}\, C_{\, 5}^{\, 6}\)
(5) \(C_{\, 0}^{\, 6}+2^{2}\, C_{\, 2}^{\, 6}+2^{4}\, C_{\, 4}^{\, 6}+2^{6}\, C_{\, 6}^{\, 6}\)
\(\Rightarrow \; \left ( x+y \right )^{6}=C_{\, 0}^{\, 6}\, x^{6}+C_{\, 1}^{\, 6}\, x^{5}y^{1}+C_{\, 2}^{\, 6}\, x^{4}y^{2}+C_{\, 3}^{\, 6}\, x^{3}y^{3}+C_{\, 4}^{\, 6}\, x^{1}y^{5}+C_{\, 6}^{\, 6}\, y^{6}\)
\(\Rightarrow \; \left ( x+y \right )^{6}=C_{\, 0}^{\, 6}\, x^{6}+C_{\, 1}^{\, 6}\, x^{5}y^{1}+C_{\, 2}^{\, 6}\, x^{4}y^{2}+C_{\, 3}^{\, 6}\, x^{3}y^{3}+C_{\, 4}^{\, 6}\, x^{1}y^{5}+C_{\, 6}^{\, 6}\, y^{6}\)
令\(\; {\color{Red} x=1},\; {\color{Green} y=\sqrt{2}}\;\)代入
\(\Rightarrow \; \left ( {\color{Red} 1}+{\color{Green} \sqrt{2}} \right )^{6}=C_{\, 0}^{\, 6}\, {\color{Red} 1^{6}}+C_{\, 1}^{\, 6}\, {\color{Red} 1^{5}}{\color{Green} \left ( \sqrt{2} \right )^{1}}+C_{\, 2}^{\, 6}\, {\color{Red} 1^{4}}{\color{Green} \left ( \sqrt{2} \right )^{2}}+C_{\, 3}^{\, 6}\, {\color{Red} 1^{3}}{\color{Green} \left ( \sqrt{2} \right )^{3}}+\) \(C_{\, 4}^{\, 6}\, {\color{Red} 1^{2}}{\color{Green} \left ( \sqrt{2} \right )^{4}}+C_{\, 5}^{\, 6}\, {\color{Red} 1^{1}}{\color{Green} \left ( \sqrt{2} \right )^{5}}+C_{\, 6}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{6}}\)
\(=C_{\, 0}^{\, 6}+C_{\, 1}^{\, 6}{\color{Green} \left ( \sqrt{2} \right )^{1}}+C_{\, 2}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{2}}+C_{\, 3}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{3}}+C_{\, 4}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{4}}+C_{\, 5}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{5}}+C_{\, 6}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{6}}\)
\(=C_{\, 0}^{\, 6}+C_{\, 1}^{\, 6}{\color{Green} \left ( \sqrt{2} \right )^{1}}+C_{\, 2}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{2}}+C_{\, 3}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{3}}+C_{\, 4}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{4}}+C_{\, 5}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{5}}+C_{\, 6}^{\, 6}\, {\color{Green} \left ( \sqrt{2} \right )^{6}}\)
\(=C_{\, 0}^{\, 6}+C_{\, 1}^{\, 6}{\color{Green} \left ( \sqrt{2} \right )}+C_{\, 2}^{\, 6}\, \times 2+C_{\, 3}^{\, 6}\, {\color{Green} \left ( 2\sqrt{2} \right )}+C_{\, 4}^{\, 6}\, \times 4+C_{\, 5}^{\, 6}\, {\color{Green} \left ( 2^{2}\sqrt{2} \right )}+C_{\, 6}^{\, 6}\, \times 8\)
\(=C_{\, 0}^{\, 6}+2\, C_{\, 2}^{\, 6}+4\, C_{\, 4}^{\, 6}+8\, C_{\, 6}^{\, 6}+\left ( C_{\, 1}^{\, 6}+2\, C_{\, 3}^{\, 6}\, +2^{2}\, C_{\, 5}^{\, 6}\, \right ){\color{Green} \left ( \sqrt{2} \right )}\)
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