H= 1/4.2/6.3/8....30/62.31/64
tìm x biết:
1/4.2/6.3/8. ... .30/62.31/64=2x
\(\frac{1}{4}\times\frac{2}{6}\times\frac{3}{8}\times...\times\frac{30}{62}\times\frac{31}{64}=2^x\)
\(\Rightarrow\) \(\frac{1\times2\times3\times...\times30\times31}{4\times6\times8\times...\times62\times64}=2^x\)
\(\Rightarrow\frac{1}{2^{31}}=2^x\)\(\Rightarrow1=2^x\times2^{31}\)
\(\Rightarrow2^{x+31}=2^0\)
\(\Rightarrow x+31=0\Rightarrow x=\left(-31\right)\)
tinh H=1/4.2/6.3/8.4/10......30/62.31/64
H = 1/4 . 2/6 . 3/8 . 4/10. ... . 30/62 . 31/64
H= 1/2.2 . 2/2.3 . 3/2.4 . 4/2.5 . ... . 30/2.31 . 31/2.32
H = 1/2 . 1/2 . 1/2 . 1/2 . ... . 1/2 . 1/32 (31 số 1/2)
H = 1/2^31 . 1/2^5
H = 1/2^36
Vậy H = 1/2^36
tìm x biết:
1/4.2/6.3/8. ... .30/62.31/64=2x
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
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=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