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

## Toán Lớp 9: 1/ Tính. ====- √53 ²-28 ² ; 2/ √11 -3 – √11 ==== ==== √4-2 √3 –

Toán Lớp 9: 1/ Tính.
————-
√53 ²-28 ² ; 2/ √11 -3 – √11

———— ————
√4-2 √3 – √ 4-2 √3
2/ Giải pt.
a/ x-5 √x + x =0
b/ ———- ———
√ 2x-1 = √ 3x-5
mọi người giúp mik với ak

$\begin{array}{l} 1)\sqrt {{{53}^2} – {{28}^2}} \\ = \sqrt {\left( {53 – 28} \right).\left( {53 + 28} \right)} \\ = \sqrt {25.81} \\ = 5.9\\ = 45\\ 2)\sqrt {11} – 3 – \sqrt {11} = – 3\\ 3)\sqrt {4 – 2\sqrt 3 } = \sqrt {3 – 2.\sqrt 3 .1 + 1} \\ = \sqrt {{{\left( {\sqrt 3 – 1} \right)}^2}} \\ = \sqrt 3 – 1\\ B2)\\ a)Dkxd:x \ge 0\\ x – 5\sqrt x + x = 0\\ \Leftrightarrow 2x – 5\sqrt x = 0\\ \Leftrightarrow \sqrt x \left( {2\sqrt x – 5} \right) = 0\\ \Leftrightarrow x = 0;x = \dfrac{{25}}{4}\\ Vậy\,x = 0;x = \dfrac{{25}}{4}\\ b)Dkxd:\left\{ \begin{array}{l} 2x – 1 \ge 0\\ 3x – 5 \ge 0 \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l} x \ge \dfrac{1}{2}\\ x \ge \dfrac{5}{2} \end{array} \right. \Leftrightarrow x \ge \dfrac{5}{2}\\ \sqrt {2x – 1} = \sqrt {3x – 5} \\ \Leftrightarrow 2x – 1 = 3x – 5\\ \Leftrightarrow x = 4\left( {tm} \right)\\ Vậy\,x = 4 \end{array}$