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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 11: tìm txd hàm số y=căn tan^2x+1/sin4x-1 y=2x+1/tan^2x+1

Toán Lớp 11: tìm txd hàm số
y=căn tan^2x+1/sin4x-1
y=2x+1/tan^2x+1

Comments ( 2 )

  1. ~rai~
    \(a)y=\dfrac{\sqrt{\tan^2x+1}}{\sin4x-1}\\ĐKXĐ:\begin{cases}\tan^2x+1\ge 0\quad\text{(luôn đúng vì }\tan^2x+1\ge 1\quad\forall x\in\mathbb{R})\\\sin4x\ne 1\end{cases}\\\Leftrightarrow 4x\ne\dfrac{\pi}{2}+k2\pi\\\Leftrightarrow x\ne\dfrac{\pi}{8}+k\dfrac{\pi}{2}.(k\in\mathbb{Z})\\TXĐ:D=\mathbb{R}\backslash\left\{\dfrac{\pi}{8}+k\dfrac{\pi}{2}\Big|k\in\mathbb{Z}\right\}.\\b)y=\dfrac{2x+1}{\tan^2x+1}\\ĐKXĐ:\begin{cases}\cos^2x\ne 0\\\tan^2x+1\ne 0\quad\text{(luôn đúng vì }\tan^2x+1\ge 1\quad\forall x\in\mathbb{R})\end{cases}\\\Leftrightarrow \cos x\ne 0\\\Leftrightarrow x\ne\dfrac{\pi}{2}+k\pi.(k\in\mathbb{Z})\\TXĐ:D=\mathbb{R}\backslash\left\{\dfrac{\pi}{2}+k\pi\Big|k\in\mathbb{Z}\right\}.\)

  2. Giải đáp:
    $\begin{array}{l}
    y = \sqrt {{{\tan }^2}x}  + \dfrac{1}{{\sin 4x}} – 1\\
    Dkxd:\left\{ \begin{array}{l}
    \cos x\# 0\\
    {\tan ^2}x \ge 0\left( {tm} \right)\\
    \sin 4x\# 0
    \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
    x\# \dfrac{\pi }{2} + k\pi \\
    4x\# k\pi 
    \end{array} \right.\\
     \Leftrightarrow \left\{ \begin{array}{l}
    x\# \dfrac{\pi }{2} + k\pi \\
    x\# \dfrac{{k\pi }}{4}
    \end{array} \right.\\
     \Leftrightarrow x\# \dfrac{{k\pi }}{4}\\
    Vậy\,TXD:D = \,R\backslash \left\{ {\dfrac{{k\pi }}{4}/k \in Z} \right\}\\
    y = \dfrac{{2x + 1}}{{{{\tan }^2}x + 1}}\\
    Dkxd:\left\{ \begin{array}{l}
    {\tan ^2}x + 1\# 0\left( {tm} \right)\\
    \cos x\# 0
    \end{array} \right.\\
     \Leftrightarrow x\# \dfrac{\pi }{2} + k\pi \\
    Vậy\,TXD:D = R\backslash \left\{ {\dfrac{\pi }{2} + k\pi /k \in Z} \right\}
    \end{array}$

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222-9+11+12:2*14+14 = ? ( )

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