Question

tim x)x.(x+4)+4.(x+4)=36

6\(^{x-2}\)=36

so sanh  )\(\frac{139}{140}\)va \(\frac{140}{141}\)

Answer 1

x.(x + 4) + 4.(x + 4) = 36

=> (x + 4).(x + 4) = 36

=> (x + 4)² = 36

=> \(\orbr{\begin{cases}x+4=6\\x+4=-6\end{cases}}\)=> \(\orbr{\begin{cases}x=2\\x=-10\end{cases}}\)

6^x-2 = 36 

=> 6^x-2 = 6²

=> x - 2 = 2

=> x = 2 + 2

=> x = 4

Ta có:

\(\frac{139}{140}=1-\frac{1}{140};\frac{140}{141}=1-\frac{1}{141}\)

Vì \(\frac{1}{140}>\frac{1}{141}\)=> \(1-\frac{1}{140}< 1-\frac{1}{141}\)

=> \(\frac{139}{140}< \frac{140}{141}\)