Question

f) \(\sqrt{x^2-8x-9}\)

giải chi tiết hộ mình ạ !!!

Answer 1

đề?

Answer 2

\(\sqrt{x^2-8x-9}=\sqrt{\left(x-9\right)\left(x+1\right)}\)

ĐKXĐ: \(\left(x-9\right)\left(x+1\right)\ge0\Leftrightarrow\left[{}\begin{matrix}x\le-1\\x\ge9\end{matrix}\right.\)

Answer 3

đề đâu 

Answer 4

\(\sqrt{x^2-8x-9}\\ =\sqrt{x^2-8x+16-25}\\=\sqrt{\left(x^2-8x+16\right)-25}\\ =\sqrt{\left(x-4\right)^2-5^2}\\ =\sqrt{\left(x-9\right)\left(x+1\right)}\\ =\sqrt{x-9}\sqrt{x+1}\)

Answer 5

ĐKXĐ: \(\left[{}\begin{matrix}x\ge9\\x\le-1\end{matrix}\right.\)