6​^2x = 216

Mà 6³ = 216

=> 2x = 3

x = 3 ÷ 2

x = 1,5

\(6^{2x}=216\)

\(\Leftrightarrow6^{2x}=6^3\)

\(\Leftrightarrow2x=3\)

\(\Leftrightarrow x=\frac{3}{2}\)

 \(\frac{1}{2\cdot2}+\frac{1}{3\cdot3}+\frac{1}{4\cdot4}+....+\frac{1}{10\cdot10}\)

Ta có : 

\(\frac{1}{2\cdot2}< \frac{1}{1\cdot2}\)

\(\frac{1}{3\cdot3}< \frac{1}{2\cdot3}\)

\(\frac{1}{4\cdot4}< \frac{1}{3\cdot4}\)

.....................................

\(\frac{1}{10\cdot10}< \frac{1}{9\cdot10}\)

Ta có : 

\(\frac{1}{2\cdot2}+\frac{1}{3\cdot3}+\frac{1}{4\cdot4}+...+\frac{1}{10\cdot10}< \frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{9\cdot10}\)

\(\frac{1}{2\cdot2}+\frac{1}{3\cdot3}+\frac{1}{4\cdot4}+...+\frac{1}{10\cdot10}< \frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\)

\(\frac{1}{2\cdot2}+\frac{1}{3\cdot3}+\frac{1}{4\cdot4}+...+\frac{1}{10\cdot10}< \frac{1}{1}-\frac{1}{10}\)

\(\frac{1}{2\cdot2}+\frac{1}{3\cdot3}+\frac{1}{4\cdot4}+...+\frac{1}{10\cdot10}< \frac{9}{10}\)

\(\Rightarrow\frac{1}{2\cdot2}+\frac{1}{3\cdot3}+\frac{1}{4\cdot4}+...+\frac{1}{10\cdot10}< \frac{9}{10}< 1\)

Đặt \(B=\frac{1}{2.2}+\frac{1}{3.3}+\frac{1}{4.4}+...+\frac{1}{10.10}\)

\(\Rightarrow B< \frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{9.10}\)

\(\Rightarrow B< 1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{9}-\frac{1}{10}\)

\(\Rightarrow B< 1-\frac{1}{10}< 1\)

\(\Rightarrow B< 1\left(đpcm\right)\)

Tổng của số bị trừ và hiệu là: 490 : 2 = 245

Số trừ là: (245 - 129) : 2 = 58

Số bị trừ là: 490 - 245 = 245

Số trừ: 58

Số bị trừ: 245

k nha

 33333.33334 nha bạn

11111 x 22222

k mik nha

\(2\cdot\left(2x-6\right)+\left(x-1\right)=2\)

\(\Leftrightarrow4x-12+x-1-2=0\)

\(\Leftrightarrow5x-15=0\)

\(\Leftrightarrow5x=15\)

\(\Leftrightarrow x=3\)

\(\overline{ab}.101=\overline{ab}.100+\overline{ab}=\overline{ab00}+\overline{ab}=\overline{abab}\)

ab.101=abab
ab.101=ab.100+ab
ab.101=ab.(100+1)
ab.101=ab.101
 

link tham khảo : https://olm.vn/hoi-dap/question/981572.html 

~ học tốt ~

x + 1234 - 532 = 2907

x + 1234         = 2907 + 532

x + 1234         = 3439

x                    = 3439 - 1234

x                    = 2205

x+1234-532=2907

=> x+702=2907

=> x=2907-702

=> x=2205

24 km nha !

k nha