Question

Cho biểu thức: \(M=\dfrac{a}{\sqrt{a^2-b^2}}-\left(1+\dfrac{a}{\sqrt{a^2-b^2}}\right):\dfrac{b}{a-\sqrt{a^2-b^2}}\). Tìm ĐKXĐ của M

Answer 1

ĐKXĐ : \(\left\{{}\begin{matrix}a^2-b^2>0\\a-\sqrt{a^2-b^2}\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a^2>b^2\\a^2-b^2\ne a^2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a^2>b^2\\b^2\ne0\end{matrix}\right.\)

Answer 2

Lời giải:
ĐKXĐ: \(\left\{\begin{matrix} a^2-b^2>0\\ a-\sqrt{a^2-b^2}\neq 0\end{matrix}\right.\Leftrightarrow \left\{\begin{matrix} a^2>b^2\\ a\neq \sqrt{a^2-b^2}\end{matrix}\right.\)

\(\Leftrightarrow \left\{\begin{matrix} a^2> b^2\\ a\neq \sqrt{a^2-b^2}\end{matrix}\right.\)