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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 9: Rút gọn D = ($\frac{2+√a}{2-√a}$-$\frac{2-√a}{2+√a}$-$\frac{4a}{4-a}$):($\frac{2}{2-√a}$-$\frac{√a+3}{2√a-a}$)

Toán Lớp 9: Rút gọn D = ($\frac{2+√a}{2-√a}$-$\frac{2-√a}{2+√a}$-$\frac{4a}{4-a}$):($\frac{2}{2-√a}$-$\frac{√a+3}{2√a-a}$)

Comments ( 1 )

  1. Giải đáp:
    $\displaystyle D=\frac{4a-4a\sqrt{a}}{\sqrt{a} -3}$
    Lời giải và giải thích chi tiết:
    $\displaystyle \begin{array}{{>{\displaystyle}l}} D=\left(\frac{2+\sqrt{a}}{2-\sqrt{a}} -\frac{2-\sqrt{a}}{2+\sqrt{a}} -\frac{4a}{4-a}\right) :\left(\frac{2}{2-\sqrt{a}} -\frac{\sqrt{a} +3}{2\sqrt{a} -a}\right)\\ ĐKXĐ:\ a\geqslant 0\ và\ a\neq 4\\ D=\left(\frac{\left( 2+\sqrt{a}\right)^{2} -\left( 2-\sqrt{a}\right)^{2} -4a}{\left( 2-\sqrt{a}\right)\left( 2+\sqrt{a}\right)}\right) :\left(\frac{2\sqrt{a} -\sqrt{a} -3}{\sqrt{a}\left( 2-\sqrt{a}\right)}\right)\\ =\frac{4\sqrt{a} -4a}{\left( 2-\sqrt{a}\right)\left( 2+\sqrt{a}\right)} .\frac{\sqrt{a}\left( 2-\sqrt{a}\right)}{\sqrt{a} -3} =\frac{4a-4a\sqrt{a}}{\sqrt{a} -3} \end{array}$

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222-9+11+12:2*14+14 = ? ( )