1/2.2/6.3/8.4/10.5/12.......30/62.31/64=1/2^x
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\(\Leftrightarrow\dfrac{2\cdot3\cdot...\cdot31}{\left(2\cdot3\cdot...\cdot31\right)\cdot\left(2\cdot2\cdot...\cdot2\right)\cdot2^6}=2^x\)
=>2^x=1/2^36
=>x=-36
(1.2.3.4.5....31)/(2(1.2.3.4.5.....31).64)=2x
1/(2.64)=2x
1/128=2x
2-7=2x
=>x=-7
ta co: 1/4=1/2(1+1) ;
2/6 = 1+1/2(2+1).....
=>ve trai =n/2(n+1).(n+1)/2(n+2).(n+2)/2(n+3).....
= (1/2)^36
=> n= - 36
\(\dfrac{1}{4}.\dfrac{2}{6}.\dfrac{3}{8}.....\dfrac{31}{64}\)
\(=\dfrac{2.3.....31}{\left(2.3.4.....31\right).\left(2.2.2.....2\right).2^6}\)(Ở phần 2 . 2 . 2 . ... . 2 có 30 số 2)
\(=\dfrac{1}{2^{30+6}}=\dfrac{1}{2^{36}}\)
\(\Rightarrow\dfrac{1}{2^{36}}=2^x\)
\(\Rightarrow2^{36}=2^{0-x}\)
\(\Rightarrow36=0-x\)
\(\Rightarrow x=-36\)
a) (x-1)^x +2 = (x-1)^x +4
(x-1)^x - (x-1)^x = 4-2
0x = 2
=> \(x=\varphi\)
b) \(\frac{1}{4}\cdot\frac{2}{6}\cdot\frac{3}{8}\cdot\frac{4}{10}\cdot\frac{5}{12}\cdot...\cdot\frac{30}{62}\cdot\frac{31}{64}=2^x\)
\(\frac{1\cdot2\cdot3\cdot4...\cdot30\cdot31}{2^{32}\left(1\cdot2\cdot3\cdot4\cdot...\cdot30\cdot31\right)\cdot32}=2^x\)
\(\frac{1}{64}=2^x\)
\(2^{-6}=2^x\)
\(x=-6\)
\(\dfrac{1}{2}\cdot\dfrac{2}{6}\cdot\dfrac{3}{8}\cdot...\cdot\dfrac{30}{62}\cdot\dfrac{31}{64}=\dfrac{1}{2^x}\)
=>\(\dfrac{2}{2}\cdot\dfrac{3}{6}\cdot\dfrac{4}{8}\cdot...\cdot\dfrac{30}{60}\cdot\dfrac{31}{62}\cdot\dfrac{1}{64}=\dfrac{1}{2^x}\)
=>\(\dfrac{1}{2}\cdot\dfrac{1}{2}\cdot...\cdot\dfrac{1}{2}\cdot\dfrac{1}{64}=\dfrac{1}{2^x}\)
=>\(\dfrac{1}{2^{29}}\cdot\dfrac{1}{2^6}=\dfrac{1}{2^x}\)
=>x=29+6=35
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