1.tính
a) 3 -(-2/7)^0 + (1/2)^2 chia 2
b) (5^2) -(-5^2)+ ((-2)^3)^2
C) 2^3 + 3(1/2)^0 - 2^-2 . 4+[(-2)^2 chia 1/2 ] .8
d) 2^2 - 2^3 +2^4 +2^5 +.........+2^44+2^45
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(2-\frac{x}{13}\right)^3=\frac{1331}{2197}\)
=> \(\left(2-\frac{x}{13}\right)^3=\left(\frac{11}{13}\right)^3\)
=> \(2-\frac{x}{13}=\frac{11}{13}\)
=> \(\frac{x}{13}=2-\frac{11}{13}=\frac{2\cdot13-11}{13}=\frac{15}{13}\)
=> x = 15
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có : \(\frac{2^9}{3^{2010}}:\frac{3^9}{2^{2010}}=\frac{2^{2019}}{3^{2019}}=\left(\frac{2}{3}\right)^{2019}< 1^{2019}=1\)
Vì \(\frac{2^9}{3^{2010}}:\frac{3^9}{2^{2010}}< 1\)
=> \(\frac{2^9}{3^{2010}}< \frac{3^9}{2^{2010}}\)
Bài làm :
Cách 1:
Ta có :
\(\frac{2^9}{3^{2010}}\div\frac{3^9}{2^{2010}}=\frac{2^9.2^{2010}}{3^{2010}.3^9}=\frac{2^{2019}}{3^{2019}}=\left(\frac{2}{3}\right)^{2019}< 1\)
\(\Rightarrow\frac{2^9}{3^{2010}}< \frac{3^9}{2^{2010}}\)
Cách 2 :
Nhận thấy :
- 29 < 39
- 32010 > 22010
\(\Rightarrow\frac{2^9}{3^{2010}}< \frac{3^9}{2^{2010}}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a ) Vì Oa ⊥⊥ OM
=> aOmˆaOm^ = 90o
Mà MOaˆMOa^ + aONˆaON^ = MONˆMON^
=> aOnˆaOn^ = MONˆMON^ - MOaˆMOa^ = 120o - 90o = 30o
Vậy aONˆaON^ = 30o
Vì Ob ⊥⊥ ON
=> bONˆbON^ = 90o
Mà bOMˆbOM^ + bONˆbON^ = MONˆMON^
=> bOMˆbOM^= MONˆMON^ - bONˆbON^ = 120o - 90o = 30o
Vậy bOMˆbOM^ = aONˆ
![](https://rs.olm.vn/images/avt/0.png?1311)
Bg
a) Ta có A = \(\frac{2x-1}{x-1}\)(x \(\inℤ\))
Để A nguyên thì 2x - 1 \(⋮\)x - 1
=> 2(x - 1) + 1 \(⋮\)x - 1
Mà 2(x - 1) \(⋮\)x - 1
Nên 1 \(⋮\)x - 1
=> x - 1 \(\in\)Ư(1)
=> x - 1 = 1 hay -1
=> x = {2; 0}
Vậy x = {2; 0}
b) Ta có:B =\(\frac{3x+4}{x+1}\)(x \(\inℤ\))
.....
=> 3x + 4 \(⋮\)x + 1
=> 3(x + 1) + 1 \(⋮\)x + 1
......
Nên 1 \(⋮\)x + 1
......
c) Ta có: C = \(\frac{4-3x}{2x+5}\)(x \(\inℤ\))
......
=> 4 - 3x \(⋮\)2x + 5
=> 2.(4 - 3x) + 3.(2x + 5) \(⋮\)2x + 5
=> 8 - 6x + 6x + 15 \(⋮\)2x + 5
=> 23 \(⋮\)2x + 5
=> 2x + 5 \(\in\)Ư(23)
....... (Tụ làm, có gì ko hiểu cứ hỏi)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có : \(\frac{9}{2}-\frac{1}{2}\cdot\frac{4}{9}=\frac{9}{2}-\frac{1}{1}\cdot\frac{2}{9}=\frac{9}{2}-\frac{2}{9}=\frac{77}{18}\)
=> \(\frac{a}{b}=\frac{77}{18}\)
<=> a = 77,b = 18
+) Có a - 2b = 77 - 2.18 = 41
Vậy a - 2b = 41