Câu 12: B

Câu 11: C

Câu 13: B

Câu 14: A

Câu 15: A

Câu 17: B

Câu 18: B

Câu 19: B

Câu 20: B

Câu 1: A

Câu 2: A

Câu 3: D

Câu 4: B

Câu 5: D

Câu 6: A

Câu 7: D

Câu 8: D

Câu 9: A

Câu 10: C

C

 C . don't live 

B

Bài 3:

\(a.2^{2x-4}=32\\ =>2^{2x-4}=2^5\\ =>2x-5=5\\ =>2x=5+4=9\\ =>x=\dfrac{9}{2}\\ b.25:\left(0,2\right)^x=1\\ =>\left(0,2\right)^x=25:1\\ =>\left(0,2\right)^x=25\\ =>\left(0,2\right)^x=\left(0,2\right)^{-2}\\ =>x=-2\\ c.85^x:17^x=625\\ =>\left(85:17\right)^x=625\\ =>5^x=5^4\\ =>x=4\\ d.\left(x+2\right)^4=\left(x+2\right)^6\\ =>\left(x+2\right)^6-\left(x+2\right)^4=0\\ =>\left(x+2\right)^4\left[\left(x+2\right)^2-1\right]=0\\ TH1:\left(x+2\right)^4=0\\ =>x+2=0=>x=-2\\ TH2:\left(x+2\right)^2-1=0\\ =>\left(x+2\right)^2=1=>x+2=\pm1\) 

+) x + 2 = 1 => x = -1

+) x + 2 = -1 => x = -3 

$#flo$

Bài 2:

`(5x + 7)^3 = 125`

`=>( 5x + 7)^3 = 5^3`

`=>5x + 7 = 5`

`=> 5x = -2`

`=> x = -2/5`

`b) (3x - 1/7)^2 = 16/49`

`=> (3x - 1/7)^2 = (4/7)^2`

`=> 3x - 1/7 = 4/7`

`=> 3x         = 5/7`

`=>  x           = 5/21`

`c) (x + 0,5)^4 = (2x)^4`

`=> x + 0,5 = 2x`

`=> x  - 2x = -0,5`

`=> -x = -0,5

`=> x = 0,5`

a.√12 = 3.46410161514 ,√7 = 2.64575131106 vậy 3.46410161514 > 2.64575131106 nên √12 > √7

b.√9+16 = √25 = 5,√9 + √16 = 3 + 4 = 7 vậy 5 < 7 nên √9+16 < √9 + √16

c.√24 = 4.89897948557,√5 = 2.2360679775 vậy 4.89897948557 > 2.2360679775 nên √24 > √5

d.6√5 = 13.416407865,5√6 = 12.2474487139 vậy 13.416407865 > 12.2474487139 nên 6√5 > 5√6

a) Ta có:

\(12>7=>\sqrt{12}>\sqrt{7}\)

b) Ta có: 

\(\sqrt{9+16}=\sqrt{25}=5\)

\(\sqrt{9}+\sqrt{16}=3+4=7\)

Vì: \(5< 7=>\sqrt{9+16}< \sqrt{9}+\sqrt{16}\)

c) Ta có: 

\(24>5=>\sqrt{24}>\sqrt{5}\)

d) Ta có: 

\(6\sqrt{5}=\sqrt{6^2\cdot5}=\sqrt{180}\\ 5\sqrt{6}=\sqrt{5^2\cdot6}=\sqrt{150}\)

Vì: \(180>150=>\sqrt{180}>\sqrt{150}=>6\sqrt{5}>5\sqrt{6}\)

1. C

2. A (are going to hold sẽ hợp hơn)

3. A

4. B

5. B

9. A

10. B

11.  D