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giúp mình với ạ.mình đang cần gấp,8 giờ hết hạn nha
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Đáp án:
2) B=-1
Giải thích các bước giải:
\(\begin{array}{l}
1)M = 2\sqrt 3 – 4\sqrt 3 = – 2\sqrt 3 \\
N = \sqrt 2 – 1 + 2\sqrt 2 – 3\sqrt 2 = – 1\\
P = \sqrt {5 – 2.\sqrt 5 .1 + 1} – \dfrac{4}{{\sqrt 5 }} + \dfrac{2}{{\sqrt 5 }}\\
= \sqrt {{{\left( {\sqrt 5 – 1} \right)}^2}} – \dfrac{4}{{\sqrt 5 }} + \dfrac{2}{{\sqrt 5 }}\\
= \sqrt 5 – 1 – \dfrac{2}{{\sqrt 5 }} = \dfrac{{3\sqrt 5 }}{5} – 1\\
2)A = \sqrt 3 – \dfrac{{2\left( {\sqrt 3 + 1} \right)}}{{3 – 1}}\\
= \sqrt 3 – \dfrac{{2\sqrt 3 + 2}}{2}\\
= \sqrt 3 – \sqrt 3 – 1 = – 1\\
B = \dfrac{{\sqrt 5 \left( {\sqrt 2 – \sqrt 5 } \right)}}{{\sqrt 2 – \sqrt 5 }} – \dfrac{{4\left( {\sqrt 5 + 1} \right)}}{{5 – 1}}\\
= \sqrt 5 – \dfrac{{4\left( {\sqrt 5 + 1} \right)}}{4}\\
= \sqrt 5 – \sqrt 5 – 1 = – 1
\end{array}\)