tinh H=1/4.2/6.3/8.4/10......30/62.31/64
tim x biuet 1/4.2/6.3/8.4/10...30/62.31/64=2.x
1/4.2/6.3/8.4/10.5/12.......30/62.31/64=2^x
\(\Leftrightarrow\dfrac{2\cdot3\cdot...\cdot31}{\left(2\cdot3\cdot...\cdot31\right)\cdot\left(2\cdot2\cdot...\cdot2\right)\cdot2^6}=2^x\)
=>2^x=1/2^36
=>x=-36
1/4.2/6.3/8.4/10.5/12..................30/62.31/64=2^n
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
Tìm x biết:
1/4.2/6.3/8.4/10......30/62.31/64=2^x
Trả lời
\(\frac{1}{4}.\frac{2}{6}.\frac{3}{8}.\frac{4}{10}.....\frac{30}{62}.\frac{31}{64}=2^x\)
\(\Leftrightarrow\frac{1}{2.2.2....2.64}=2^x\) ( 30 số hạng 2 )
\(\Leftrightarrow\frac{1}{2^{30}.2^6}=2^x\)
\(\Leftrightarrow\frac{1}{2^{36}}=2^x\)
\(\Rightarrow2^x=2^{-36}\)
\(\Rightarrow x=-36\)
Vậy \(x=-36\)
1/4.2/6.3/8.4/10.5/12.....30/62.31/64=2X, tìm x
(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
tìm x biết: 1/4.2/6.3/8.4/10.5/12....30/62.31/64=2x
Tìm x biết:
1/4.2/6.3/8.4/10.5/12.....30/62.31/64=2^x
tìm x
1/4.2/6.3/8.4/10.5/12...30/62.31/64=4x
Tìm x,y,z 1/4.2/6.3/8.4/10.5/12.......30/62.31/64=2^x
\(\dfrac{1}{4}.\dfrac{2}{6}.\dfrac{3}{8}.....\dfrac{31}{64}\)
\(=\dfrac{2.3.....31}{\left(2.3.4.....31\right).\left(2.2.2.....2\right).2^6}\)(Ở phần 2 . 2 . 2 . ... . 2 có 30 số 2)
\(=\dfrac{1}{2^{30+6}}=\dfrac{1}{2^{36}}\)
\(\Rightarrow\dfrac{1}{2^{36}}=2^x\)
\(\Rightarrow2^{36}=2^{0-x}\)
\(\Rightarrow36=0-x\)
\(\Rightarrow x=-36\)