Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a)\(\forall x\Rightarrow sinx\le1\Rightarrow1-sinx\ge0\)
cosx\(\ge-1\Rightarrow1+cosx\ge0\)
ĐK:cosx\(\ne-1\Leftrightarrow x\ne\pi+k2\pi\)
\(\Rightarrow D=\left\{R\backslash\left\{\pi+k2\pi\right\}\right\}\)
b)ĐK:\(cos\left(2x+\frac{\pi}{3}\right)\ne0\Leftrightarrow2x+\frac{\pi}{3}\ne\frac{\pi}{2}+k\pi\Leftrightarrow x\ne\frac{\pi}{12}+\frac{k\pi}{2}\)
\(\Rightarrow D=\left\{R\text{\}\left\{\frac{\pi}{12}+\frac{k\pi}{2}\right\}\right\}\)
Cộng đồng học tập online | Học trực tuyến
Lần sau có bài em đăng trong link này để đc các bạn giúp đỡ nhé!
+)\(y=\frac{1}{\sqrt{1+\cos4x}}\)
ĐKXĐ: \(\cos4x+1>0\Leftrightarrow\cos4x>-1\Leftrightarrow\cos4x\ne-1\)
\(\Leftrightarrow4x\ne\pi+k2\pi\Leftrightarrow x\ne\frac{\pi}{4}+\frac{k\pi}{2}\), k thuộc Z
TXĐ: \(ℝ\backslash\left\{\frac{\pi}{4}+\frac{k\pi}{2}\right\}\), k thuộc Z
+) \(y=\sqrt{\tan x-\sqrt{3}}\)
ĐKXĐ: \(\hept{\begin{cases}\tan x-\sqrt{3}\ge0\\x\ne\frac{\pi}{2}+k\pi\end{cases}\Leftrightarrow\hept{\begin{cases}\tan x\ge\tan\frac{\pi}{3}\\x\ne\frac{\pi}{2}+k\pi\end{cases}\Leftrightarrow}\frac{\pi}{3}+k\pi\le x< \frac{\pi}{2}+k\pi}\)
TXĐ:...
1.
ĐKXĐ: \(sin\left(2x+3\right)\ne0\Leftrightarrow2x+3\ne k\pi\)
\(\Leftrightarrow x\ne-\frac{3}{2}+\frac{k\pi}{2}\)
2.
ĐKXĐ: \(\left\{{}\begin{matrix}cos2x\ne0\\sinx\ne-1\\sin\left(3x+\frac{\pi}{6}\right)\ne0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}2x\ne\frac{\pi}{2}+k\pi\\x\ne-\frac{\pi}{2}+k2\pi\\3x+\frac{\pi}{6}\ne k\pi\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ne\frac{\pi}{4}+\frac{k\pi}{2}\\x\ne-\frac{\pi}{2}+k2\pi\\x\ne-\frac{\pi}{18}+\frac{k\pi}{3}\end{matrix}\right.\)
3.
\(\left\{{}\begin{matrix}cos5x\ne0\\sin4x\ne cos3x\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}5x\ne\frac{\pi}{2}+k\pi\\sin4x\ne sin\left(\frac{\pi}{2}-3x\right)\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ne\frac{\pi}{10}+\frac{k\pi}{5}\\4x\ne\frac{\pi}{2}-3x+k2\pi\\4x\ne\frac{\pi}{2}+3x+k2\pi\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ne\frac{\pi}{10}+\frac{k\pi}{5}\\x\ne\frac{\pi}{14}+\frac{k2\pi}{7}\\x\ne\frac{\pi}{2}+k2\pi\end{matrix}\right.\)
1.
\(\left\{{}\begin{matrix}cos2x\ne0\\\sqrt{3}sin2x-cos2x\ne0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}2x\ne\frac{\pi}{2}+k\pi\\\frac{\sqrt{3}}{2}sin2x-\frac{1}{2}cos2x\ne0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ne\frac{\pi}{4}+\frac{k\pi}{2}\\sin\left(2x-\frac{\pi}{6}\right)\ne0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x\ne\frac{\pi}{4}+\frac{k\pi}{2}\\x\ne\frac{\pi}{12}+\frac{k\pi}{2}\end{matrix}\right.\)
2.
\(\left\{{}\begin{matrix}sin\left(x+\frac{\pi}{6}\right)\ne0\\cosx\ne1\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x\ne-\frac{\pi}{6}+k\pi\\x\ne k2\pi\end{matrix}\right.\)
3.
\(sin4x\ne-1\Leftrightarrow4x\ne-\frac{\pi}{2}+k2\pi\)
\(\Leftrightarrow x\ne-\frac{\pi}{8}+\frac{k\pi}{2}\)