\(A=\frac{\sqrt{x}}{\sqrt{x}+2}+\frac{\sqrt{x}+2}{\sqrt{x}-2}+\frac{2x+8}{2x-4}\)Rút gọn A
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\(A=\left(a-1\right)\sqrt{\frac{a}{a-1}}+\sqrt{a\left(a-1\right)}-a\sqrt{\frac{a-1}{a}}\)
\(A=\sqrt{\left(a-1\right)^2.\frac{a}{a-1}}+\sqrt{a\left(a-1\right)}-\sqrt{a^2.\frac{a-1}{a}}\)
\(A=\sqrt{\left(a-1\right)a}+\sqrt{a\left(a-1\right)}-\sqrt{a\left(a-1\right)}\)
\(A=\sqrt{a\left(a-1\right)}\)
\(A=\frac{\left(x+\sqrt{x^2-2x}\right)^2-\left(x-\sqrt{x^2-2x}\right)^2}{\left(x-\sqrt{x^2-2x}\right)\left(x+\sqrt{x^2-2x}\right)}\)
\(=\frac{2x\times2\sqrt{x^2-2x}}{2x}=2\sqrt{x^2-2x}\)
\(A=\frac{x+\sqrt{x^2-2x}}{x-\sqrt{x^2-2x}}-\frac{x-\sqrt{x^2-2x}}{x+\sqrt{x^2+2x}}\)
\(=\frac{\left(x+\sqrt{x^2-2x}\right)^2-\left(x-\sqrt{x^2-2x}\right)^2}{x^2-\left(\sqrt{x^2-2x}\right)^2}\)
\(=\frac{x^2+x^2-2x+2x\sqrt{x^2-2x}-\left(x^2+x^2-2x-2x\sqrt{x^2-2x}\right)}{x^2-\left(x^2-2x\right)}\)
\(=\frac{2x^2-2x-2x^2+2x+2x\sqrt{x^2-2x}+2x\sqrt{x^2-2x}}{2x}\)
\(=\frac{4x\sqrt{x^2-2x}}{2x}=2\sqrt{x^2-2x}\)
\(A=\frac{\sqrt{x}}{\sqrt{x}+2}+\frac{\sqrt{x}+2}{\sqrt{x}-2}+\frac{2x+8}{2x-4}\)
\(=\frac{\sqrt{x}\left(\sqrt{x}-2\right)+\left(\sqrt{x}+2\right)^2}{x-4}+\frac{2x+8}{2x-4}\)
\(=\frac{x-2\sqrt{x}+x+4\sqrt{x}+4}{x-4}+\frac{2x+8}{2x-4}\)
\(=\frac{2x+2\sqrt{x}+4}{x-4}+\frac{2x+8}{2x-4}\)
Quy đồng lên thử ....
Coi lại cái đề hộ -.-