Rút gọn biểu thức : $A$ = ( $\frac{12}{\sqrt{x}-1}$ +$\frac{12}{1+\sqrt{x}}$ ):$\frac{2017}{x-1}$ với ($x$ $\geq$ 0; x$\neq$ 1)
2 câu trả lời
`A=(12/(\sqrt{x}-1)+12/(1+\sqrt{x})):2017/(x-1)`
`ĐKXĐ:x>0n; x\ne 1`
`<=>A=(12/(\sqrt{x}-1)+12/(\sqrt{x}+1)):2017/((\sqrt{x})²-1²)`
`<=>A=(12/(\sqrt{x}-1)+12/(\sqrt{x}+1)):2017/((\sqrt{x}-1)(\sqrt{x}+1))`
`<=>A=((12(\sqrt{x}+1))/((\sqrt{x}-1)(\sqrt{x}+1))+(12(\sqrt{x}-1))/((\sqrt{x}-1)(\sqrt{x}+1)) ):2017/((\sqrt{x}-1)(\sqrt{x}+1))`
`<=>A=((12\sqrt{x}+12)/((\sqrt{x}-1)(\sqrt{x}+1))+(12\sqrt{x}-12)/((\sqrt{x}-1)(\sqrt{x}+1))):2017/((\sqrt{x}-1)(\sqrt{x}+1))`
`<=>A=(12\sqrt{x}+12+12\sqrt{x}-12)/((\sqrt{x}-1)(\sqrt{x}+1)):2017/((\sqrt{x}-1)(\sqrt{x}+1))`
`<=>A=((12+12)\sqrt{x}+(12-12))/((\sqrt{x}-1)(\sqrt{x}+1)). ((\sqrt{x}-1)(\sqrt{x}+1))/2017`
`<=>A=(24\sqrt{x})/((\sqrt{x}-1)(\sqrt{x}+1)).((\sqrt{x}-1)(\sqrt{x}+1))/2017`
`<=>A=(24\sqrt{x}(\sqrt{x}-1)(\sqrt{x}+1))/((\sqrt{x}-1)(\sqrt{x}+1).2017)`
`<=>A=(24\sqrt{x})/2017` ( giản ước `(\sqrt{x}-1)(\sqrt{x}+1)` )
Vậy `A=(24\sqrt{x})/2017`
$\textit{Đáp án + Giải thích các bước giải:}$
`A=(12/(\sqrt{x}-1)+12/(1+\sqrt{x})):2017/(x-1)` `(x \ge 0,x \ne 1)`
`=[(12(\sqrt{x}+1))/((\sqrt{x}-1)(\sqrt{x}+1))+(12(\sqrt{x}-1))/((\sqrt{x}-1)(\sqrt{x}+1))].(x-1)/2017`
`=(12\sqrt{x}+12+12\sqrt{x}-12)/((\sqrt{x})^2-1^2).(x-1)/2017`
`=(24\sqrt{x})/(x-1).(x-1)/2017`
`=(24\sqrt{x})/2017`