So sánh 212 và 39
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)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{18}{109}\)< \(\frac{5}{30}\)
\(\frac{52}{21}\)<\(\frac{523}{212}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Nếu m=7 thì P=198+33×m−225=198+33×7−225=198+231−225=429−225=204
Nếu m=7 thì Q=1204:m+212:4=1204:7+212:4=172+53=225
Mà 204<225
Vậy với m=7 thì P<Q.
![](https://rs.olm.vn/images/avt/0.png?1311)
Lời giải:
$A=\frac{2^{10}+2-1}{2^9+1}=\frac{2(2^9+1)-1}{2^9+1}=2-\frac{1}{2^9+1}$
$B=\frac{2^{12}+1}{2^{11}+1}=\frac{2(2^{11}+1)-1}{2^{11}+1}=2-\frac{1}{2^{11}+1}$
Vì $2^9+1< 2^{11}+1\Rightarrow \frac{1}{2^9+1}> \frac{1}{2^{11}+1}$
$\Rightarrow 2-\frac{1}{2^9+1}< 2-\frac{1}{2^{11}+1}$
$\Rightarrow A< B$
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có: \(\frac{7}{8}=\frac{1701}{1944}và\frac{212}{243}=\frac{1696}{1944}\)
Vì \(\frac{1701}{1944}>\frac{1696}{1944}nên\frac{7}{8}>\frac{212}{243}\)
Vậy \(\frac{7}{8}>\frac{212}{243}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
A = \(\overline{5ab2}\) + \(\overline{b3}\) - 120 ; B = \(\overline{43b9}\) + \(\overline{a2c}\) - \(\overline{4c}\)
A = 5002 + \(\overline{\text{ab}0}\) + \(\overline{b0}\) + 3 - 120
A = (5002 + 3 - 120) + \(\overline{ab0}\) + \(\overline{b0}\)
A = 4885 + \(\overline{ab0}\) + \(\overline{b0}\)
B = \(\overline{43b9}\) + \(\overline{a2c}\) - \(\overline{4c}\)
B = 4309 + \(\overline{b0}\) + \(\overline{a00}\) + 20 + c - 40 - c
B = (4309 + 20 - 40) + \(\overline{ab0}\)
B = 4289 + \(\overline{ab0}\)
B = 4289 + \(\overline{ab0}\) < 4885 + \(\overline{ab0}\) + \(\overline{b0}\) = A
Vậy B < A
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:\(\frac{18}{75}=\frac{6}{25}=\frac{12}{50};\frac{28}{212}=\frac{7}{53}\)
Vì \(12>7;50< 53\Rightarrow\frac{12}{50}>\frac{7}{53}\)
\(\Leftrightarrow\frac{18}{75}>\frac{28}{212}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Vì ΔABD = ΔACD (chứng minh câu a)
⇒ BD = CD (hai cạnh tương ứng)
⇒ ΔBCD cân tại D
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có: \(-\dfrac{7}{15}=\dfrac{-7\cdot39}{15\cdot39}=-\dfrac{273}{585}\)
\(\dfrac{20}{-39}=-\dfrac{20}{39}=\dfrac{-20\cdot15}{39\cdot15}=-\dfrac{300}{585}\)
Ta có: -273>-300
\(=>-\dfrac{273}{585}>-\dfrac{300}{585}hay-\dfrac{7}{15}>\dfrac{20}{-39}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1:
a: Sửa đề: 1/3^200
1/2^300=(1/8)^100
1/3^200=(1/9)^100
mà 1/8>1/9
nên 1/2^300>1/3^200
b: 1/5^199>1/5^200=1/25^100
1/3^300=1/27^100
mà 25^100<27^100
nên 1/5^199>1/3^300
212=(24)3=163
39=(33)3=273
Do 16<27 =>163<273
Vậy 212<39