a) Áp dụng định lý pytago có 

AB²+AC²=BC²

thay số 

=>BC=10cm

lx

lỗi rùi bn

4.

a, \(A=\sqrt[3]{15\sqrt{3}+26}=\sqrt[3]{\left(\sqrt{3}+2\right)^3}=\sqrt{3}+2\)

b, \(B=\sqrt[3]{5+2\sqrt{13}}+\sqrt[3]{5-2\sqrt{13}}\)

\(\Rightarrow2B=\sqrt[3]{40+16\sqrt{13}}+\sqrt[3]{40-16\sqrt{13}}\)

\(=\sqrt[3]{\left(\sqrt{13}+1\right)^3}+\sqrt[3]{\left(\sqrt{13}-1\right)^3}\)

\(=\sqrt{13}+1+\sqrt{13}-1=2\sqrt{13}\)

\(\Rightarrow B=\sqrt{13}\)

c, \(C=\sqrt[3]{182-\sqrt{33125}}+\sqrt[3]{182+\sqrt{33125}}\)

\(\Rightarrow C^3=364+3\sqrt[3]{182-\sqrt{33125}}.\sqrt[3]{182+\sqrt{33125}}\left(\sqrt[3]{182-\sqrt{33125}}+\sqrt[3]{182+\sqrt{33125}}\right)\)

\(=364-3C\)

\(\Rightarrow C^3+3C-364=0\)

\(\Leftrightarrow C=7\)

54 A

55 A

56 D

56 C

58 A

59 A

60 B

61 A

62 B

57 A

CMR : A , là gì thế bạn

Chứng minh rằng

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3, Guests

4,Lullabies

5,cultivate

1,What do the Muong people often play?

2,Which is the largest ethnic group in VN

3, Whose the Cham children are named of?

4,What are the highlights of the Muong costume?

5,Where do the Muong live in with abundant......?

\(\dfrac{7x-2}{3}-2x< 5-\dfrac{x-2}{4}\)

<=>\(\dfrac{4\left(7x-2\right)}{12}-\dfrac{24x}{12}< \dfrac{60}{12}-\dfrac{3\left(x-2\right)}{12}\)

<=>\(4\left(7x-2\right)-24x< 60-3\left(x-2\right)\)

<=>\(28x-8-24x< 60-3x+6\)

<=>\(28x+3x-24x< 60+8+6\)

<=>\(7x< 74\)

<=>x<\(\dfrac{74}{7}\)

Vậy...

bn gần thi à tự lm nhe giúp bn bn chép lại thì cx như ko nên cố lên tự lm nhe bn. Good luck!

1 B

2 A

3 D

4 C

5 C

6 A

7 B

8 D