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9 tháng 3 2021

\(\dfrac{\left(-6\right).11}{\left(-11\right).\left(-8\right)}=\dfrac{\left(-3\right).2.11}{11.2.4}=-\dfrac{3}{4}\)

\(\dfrac{21.\left(-5\right)}{25.\left(-7\right)}=\dfrac{\left(-3\right).\left(-7\right).\left(-5\right)}{\left(-5\right).\left(-5\right).\left(-7\right)}=\dfrac{3}{5}\)

\(\dfrac{32.9.11}{12.24.22}=\dfrac{4.4.2.3.3.11}{3.4.4.2.3.11.2}=\dfrac{4^2.2.3^2.11}{3^2.4^2.2^2.11}=\dfrac{1}{2}\)

9 tháng 3 2021

\(\dfrac{\left(-6\right).11}{\left(-11\right).\left(-8\right)}\)=\(\dfrac{-3}{4}\)

\(\dfrac{21.\left(-5\right)}{25.\left(-7\right)}\)=\(\dfrac{2}{5}\)

\(\dfrac{32.9.11}{12.24.22}\)=\(\dfrac{1}{2}\)

17 tháng 7 2023

1) \(\sqrt{6+4\sqrt{2}}-\sqrt{11-6\sqrt{2}}\)

\(=\sqrt{2^2+2\cdot2\cdot\sqrt{2}+\left(\sqrt{2}\right)^2}-\sqrt{3^2-2\cdot3\cdot\sqrt{2}+\left(\sqrt{2}\right)^2}\)

\(=\sqrt{\left(2+\sqrt{2}\right)^2}-\sqrt{\left(3-\sqrt{2}\right)^2}\)

\(=\left|2+\sqrt{2}\right|-\left|3-\sqrt{2}\right|\)

\(=2+\sqrt{2}-3+\sqrt{2}\)

\(=2\sqrt{2}-1\)

2) \(\sqrt{21-4\sqrt{5}}+\sqrt{21+4\sqrt{5}}\)

\(=\sqrt{20-4\sqrt{5}+1}+\sqrt{20+4\sqrt{5}+1}\)

\(=\sqrt{\left(2\sqrt{5}\right)^2-2\sqrt{5}\cdot2\cdot1+1^2}+\sqrt{\left(2\sqrt{5}\right)^2+2\sqrt{5}\cdot2\cdot1-1^2}\)

\(=\sqrt{\left(2\sqrt{5}-1\right)^2}+\sqrt{\left(2\sqrt{5}+1\right)^2}\)

\(=\left|2\sqrt{5}-1\right|+\left|2\sqrt{5}+1\right|\)

\(=2\sqrt{5}-1+2\sqrt{5}+1\)

\(=4\sqrt{5}\)

a: \(=\left(\sqrt{3}-2\right)\cdot\sqrt{\left(2+\sqrt{3}\right)^2}\)

\(=\left(\sqrt{3}-2\right)\left(\sqrt{3}+2\right)\)

=3-4=-1

b: \(=\sqrt{6+4\sqrt{2}}-\sqrt{11-2\sqrt{18}}\)

\(=\sqrt{\left(2+\sqrt{2}\right)^2}-\sqrt{\left(3-\sqrt{2}\right)^2}\)

\(=2+\sqrt{2}-3+\sqrt{2}=2\sqrt{2}-1\)

c: \(=\sqrt{\left(2\sqrt{5}-1\right)^2}+\sqrt{\left(2\sqrt{5}+1\right)^2}\)

\(=2\sqrt{5}-1+2\sqrt{5}+1\)

\(=4\sqrt{5}\)

18 tháng 1

giúp mik với ạ!!!

Câu 1: C

Câu 2: A

a: =1/4+1/4=2/4=1/2

b: =3/5+3/5=6/5

c: =5/9+7/9=12/9=4/3

a, 1/4+1/4=2/4=1/4

b, 3/5+3/5=6/5

c, 5/9+7/9=12/9=4/3