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Tìm X
\(\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)\times\left(1-\frac{1}{5}\right)\)
\(=\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}\)
\(=\frac{1}{5}\)
\(\Rightarrow x-100=\frac{1}{5}\)
\(x=\frac{1}{5}+100\)
\(x=\frac{1}{5}+\frac{500}{5}\)
\(x=\frac{501}{5}\)
<=> x : ( 1/2+1/4+1/8) x 100 = 13.25
<=> x : ( 4/8 + 2/8 + 1/8) = 13.25 : 100
<=> x : 7/8 = 0,1325
<=> x = 0,1325 x 7/8
<=> x= 0.1159375
Chả biết đúng không nữa nhưng hình như là sai ế :)
x:1/2+x:1/4+x:25/2=13,25
x:(1/2+1/4+25/2)=13,25
x:53/4=13,25
x:53/4=53/4
x=53/4x53/4
x=2809/16
ta có: \(A=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{x}.\)
\(A=1+\frac{1}{2}+\frac{1}{2.2}+\frac{1}{2.2.2}+...+\frac{1}{x}\)
\(\Rightarrow2A=2+1+\frac{1}{2}+\frac{1}{2.2}+...+\frac{1}{x:2}\)
\(\Rightarrow2A-A=2-\frac{1}{x}\)
\(A=2-\frac{1}{x}=\frac{4095}{2048}\)
=> 1/x = 1/2048
=> x = 2048 ( 2048 = 211 )
\(A=2\times4+4\times6+...+98\times100\)
\(A=2.2+2.12+...+2.149\)
\(A=2.\left(2+12+...+149\right)\)
Tự làm nốt( dấu x = dấu chấm )
(x + 1 ) + ( x + 2 ) + ( x + 3 ) + ........+ (x + 100) = 5550
x = 100 + ( 1 + 2 + 3 + .........+100)=5550
x = (5550 - 5050 ) : 100
x = 500 : 100
x = 5
\(\dfrac{1}{10}+\dfrac{2}{10}+\dfrac{3}{10}+\dfrac{4}{10}+\dfrac{5}{10}+\dfrac{6}{10}+\dfrac{7}{10}+\dfrac{8}{10}+\dfrac{9}{10}\)
\(=\left(\dfrac{1}{10}+\dfrac{9}{10}\right)+\left(\dfrac{2}{10}+\dfrac{8}{10}\right)+\left(\dfrac{3}{10}+\dfrac{7}{10}\right)+\left(\dfrac{4}{10}+\dfrac{6}{10}\right)+\dfrac{5}{10}\)
\(=1+1+1+1+\dfrac{5}{10}\)
\(=4+\dfrac{5}{10}\)
\(=\dfrac{45}{10}\)
\(13,25:0,5+13,25:0,25+13,25:0,125+13,25\times6\)
\(=13,25:\dfrac{1}{2}+13,25:\dfrac{1}{4}+13,25:\dfrac{1}{8}+13,25\times6\)
\(=13,25\times2+13,25\times4+13,25\times8+13,25\times6\)
\(=13,25\times\left(2+4+8+6\right)\)
\(=13,25\times20\)
\(=265\)
\(2A=2+1+\frac{1}{2}+\frac{1}{4}+...+\frac{2}{x}\)
=> \(2A-A=\left(2+1+\frac{1}{2}+\frac{1}{4}+...+\frac{2}{x}\right)-\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{2}{x}+\frac{1}{x}\right)\)
=> \(A=2-\frac{1}{x}\)
Giải phương trình:
\(2-\frac{1}{x}=\frac{4095}{2048}\)
\(\frac{1}{x}=2-\frac{4095}{2048}\)
\(\frac{1}{x}=\frac{1}{2048}\)
x=2048
X : 1/2 + X : 1/4 + X : 1/8 x 100 = 13,25
Xx3 + (1/2+1/4+1/8) =13,25: 100
Xx3 + 7/8 = 0,1325
Xx3= 0,1325 -7/8
Xx3= -- 0,7425
X= --0,7425 : 3
X= --0,2475
nhé bạn
X : 1/2 + X : 1/4 + X : 1/8 x 100 = 13,25
Xx3 + (1/2+1/4+1/8) =13,25: 100
Xx3 + 7/8 = 0,1325
Xx3= 0,1325 -7/8
Xx3= -- 0,7425
X= --0,7425 : 3
X= --0,2475
Ai k mk mk k lại!