Đăng bài 08-05-12 03:02 PM
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Giải các hệ : $1)\,\left\{ \begin{array}{l} {3^x}{.2^y} = \frac{1}{9}\\ y - x = 2 \end{array} \right.\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,2)\,\left\{ \begin{array}{l} {2^y} = {200.5^x}\\ x + y = 1 \end{array} \right.$
Đăng bài 08-05-12 03:00 PM
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Giải các hệ phương trình : $\begin{array}{l} 1)\,\,\,\left\{ \begin{array}{l} {y^2} = {4^x} + 8\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(1)\\ {2^{x + 1}} + y + 1 = 0\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(2) \end{array} \right.\\ 2)\,\,\left\{ \begin{array}{l} {y^2} = {4^x} + 2\,\\ {2^{x + 1}} + 2y + 1 = 0 \end{array} \right. \end{array}$
Đăng bài 08-05-12 02:57 PM
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Đăng bài 27-04-12 08:47 AM
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Đăng bài 27-04-12 08:33 AM
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Xác định $a$ để hệ sau có nghiệm duy nhất : $\left\{ \begin{array}{l} {2^{\left| x \right|}} + \left| x \right| = y + {x^2} + a\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(1)\\ {x^2} + {y^2} = 1\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(2) \end{array} \right.$
Đăng bài 27-04-12 08:30 AM
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Đăng bài 27-04-12 08:28 AM
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Giải và biện luận theo $a$ hệ sau : $\left\{ \begin{array}{l} 2cos\,x + a. \sin\,y = 1\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(1)\\ {\log _z}\sin y = {\log _z}a.{\log _a}\left( {2 - 3cos\,x} \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(2)\\ {\log _a}z + {\log _a}\left( {\frac{1}{{2a}} - 1} \right) = 0\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(3) \end{array} \right.$
Đăng bài 27-04-12 08:26 AM
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Đăng bài 27-04-12 08:19 AM
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Cho hệ phương trình : $\left\{ \begin{array}{l} 9{x^2} - 4{y^2} = 5\\ {\log _m}\left( {3x + 2y} \right) - {\log _3}\left( {3x - 2y} \right) = 1 \end{array} \right.\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(1)$ $1)$ Giải $(1)$ khi $m = 5$ $2)$ Tìm giá trị lớn nhất của tham số $m$ sao cho hệ $(1)$ có nghiệm $\left( {x,\,y} \right)$ thỏa mãn $3x + 2y \le 5$
Đăng bài 27-04-12 08:16 AM
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Giải hệ : $1)\,\,\,\left\{ \begin{array}{l} y\,\sin \,x = {\log _2}\left| {\frac{{y\,\sin \,x}}{{1 + 3y}}} \right|\\ \left( {6{y^2} + 2y} \right)\left( {{4^{{{\sin }^2}x}} + {4^{co{s^2}x}}} \right) = 25{y^2} + 6y + 1\\ \left| y \right| \le 1 \end{array} \right.$
$2)\,\,\,\left\{ \begin{array}{l} {\left( {3 - y} \right)}co{s^2}x = {\log _3}\left| {\frac{{8 + y}}{{y\left( {1 - \sin {\,^3}x} \right)}}} \right|\\ \left( {{y^2} + 8y} \right)\left( {{3^{2 + 2{{\sin }^4}x}} + {3^{2co{s^4}x + {{\sin }^2}2x - 4}}} \right) = 2{y^2} + 16y + 64\\ 1 \le y < 10 \end{array} \right.$
Đăng bài 27-04-12 08:10 AM
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Giải hệ : $\left\{ \begin{array}{l} {\log _6}\left( {\sqrt x + \sqrt[4] x} \right) = \frac{1}{4}{\log _2}x\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(1)\\ \frac{{\sin \,\frac{{16\pi }}{x}}+1}{{cos\,\frac{{x\pi }}{{16}}}} < 1 - cos\,\frac{{\sqrt x \pi }}{4}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(2) \end{array} \right.$
Đăng bài 27-04-12 08:08 AM
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Đăng bài 26-04-12 05:03 PM
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Giải các hệ : $\begin{array}{l} 1)\,\,\,\left\{ \begin{array}{l} {\log _{2 - x}}\left( {2 - y} \right) > 0\\ {\log _{4 - y}}\left( {2x - 2} \right) > 0 \end{array} \right.\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,3)\,\,\left\{ \begin{array}{l} {\log _{x - 2}}\left( {2y - 4} \right) > 0\\ {\log _{3 - y}}\left( {x - 4} \right) > 0 \end{array} \right.\\ 2)\,\,\,\left\{ \begin{array}{l} {\log _{x - 1}}\left( {5 - y} \right) < 0\\ {\log _{2 - y}}\left( {4 - x} \right) < 0 \end{array} \right. \end{array}$
Đăng bài 26-04-12 04:55 PM
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