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

Toán Lớp 9: bài 1 : thực hiện phép tính a) √27+ $\frac{1}{2}$ . √48- √108 b) √7+4√3-√(5+√3) c) ( √14-√10). $\sqrt{6+\sqrt35}$ d) $\frac{\s

Tháng Ba 26, 2023 Toán học 0 Comments 0 views

Toán Lớp 9: bài 1 : thực hiện phép tính
a) √27+ $\frac{1}{2}$ . √48- √108
b) √7+4√3-√(5+√3)
c) ( √14-√10). $\sqrt{6+\sqrt35}$
d) $\frac{\sqrt{15}+\sqrt{3}}{1+\sqrt{5}}$- $\frac{2}{\sqrt{3}-1}$

Comments ( 1 )

  1. hatuanlan
    hatuanlan
    26 Tháng Ba, 2023 at 1:30 sáng
    Reply
    a)$\sqrt{27}+\frac{1}{2}-\sqrt{48}-\sqrt{108}$
    $=3\sqrt{3}+\frac{1}{2}-4\sqrt{3}-6\sqrt{3}$
    $=\frac{1}{2}+3\sqrt{3}-4\sqrt{3}-6\sqrt{3}$
    $=\frac{1}{2}-7\sqrt{3}$
    b)$ \sqrt{7}+4\sqrt{3}-\sqrt{5+\sqrt{3}}$
    $=6.97933\dots $
    c) $\left(\sqrt{14}-\sqrt{10}\right)\sqrt{6+\sqrt{35}}$
    $=\sqrt{6+\sqrt{35}}\sqrt{14}-\sqrt{6+\sqrt{35}}\sqrt{10}$
    $=\sqrt{14}\sqrt{6+\sqrt{35}}-\sqrt{10}\sqrt{6+\sqrt{35}}$
    $=\sqrt{14}\sqrt{6+\sqrt{35}}-\sqrt{10}\sqrt{6+\sqrt{35}}$
    d) $\frac{\sqrt{15}+\sqrt{3}}{1+\sqrt{5}}-\frac{2}{\sqrt{3}-1}$
    $\frac{\sqrt{15}+\sqrt{3}}{1+\sqrt{5}}-\frac{2}{\sqrt{3}-1}$
    $=\frac{\left(\sqrt{15}+\sqrt{3}\right)\left(\sqrt{3}-1\right)-2\left(1+\sqrt{5}\right)}{\left(1+\sqrt{5}\right)\left(\sqrt{3}-1\right)}$
    $=\frac{1+\sqrt{5}-\sqrt{15}-\sqrt{3}}{\left(1+\sqrt{5}\right)\left(\sqrt{3}-1\right)}$
    $=-1$
     

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

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