1+1+1+1+1+1
ai nhanh mình tick
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Sửa đề: \(C=\dfrac{17^{99}+1}{17^{99}-1}\)
\(C=\dfrac{17^{99}-1+2}{17^{99}-1}=1+\dfrac{2}{17^{99}-1}\)
\(D=\dfrac{17^{98}-1+2}{17^{98}-1}=1+\dfrac{2}{17^{98}-1}\)
17^99>17^98
=>17^99-1>17^98-1
=>C<D
\(\left|x+1\right|+\left|x-5\right|=3x+1\left(đk:x\ge-\dfrac{1}{3}\right)\)
\(\Leftrightarrow x+1+\left|x-5\right|=3x+1\)
\(\Leftrightarrow\left|x-5\right|=2x\)
\(\Leftrightarrow\left[{}\begin{matrix}x-5=2x\left(x\ge5\right)\\x-5=-2x\left(-\dfrac{1}{3}\le x< 5\right)\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-5\left(ktm\right)\\x=\dfrac{5}{3}\left(tm\right)\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}-x-1+5-x=3x+1\left(x< -1\right)\\x+1+5-x=3x+1\left(-1\le x< 5\right)\\x+1+x-5=3x+1\left(x\ge5\right)\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{5}\left(ktm\right)\\x=\dfrac{5}{3}\left(tm\right)\\x=-5\left(ktm\right)\end{matrix}\right.\Rightarrow x=\dfrac{5}{3}\)
0,44 x (\(x+x\times\) 5 - \(\dfrac{23}{55}\)) + \(\dfrac{3}{14}\) x 2,24 = 1
0,44 x (\(x+x\times\)5 - \(\dfrac{23}{55}\)) + 0,48 = 1
0,44 x (\(x+x\times\) 5 - \(\dfrac{23}{55}\)) = 1 - 0,48
0,44 x (\(x+x\times5\) - \(\dfrac{23}{55}\)) = 0,52
\(x+x\times5\) - \(\dfrac{23}{55}\) = 0,52 : 0,44
\(x\) x (1 + 5) -\(\dfrac{23}{55}\) = \(\dfrac{13}{11}\)
\(x\) x 6 - \(\dfrac{66}{10}\) = \(\dfrac{13}{11}\) + \(\dfrac{23}{55}\)
\(x\) x 6 = \(\dfrac{65}{55}\) + \(\dfrac{23}{55}\)
\(x\times\) 6 = \(\dfrac{8}{5}\)
\(x\) x 6 = \(\dfrac{8}{5}\) : 6
\(x\) = \(\dfrac{4}{15}\)
Vậy \(x=\dfrac{4}{15}\)
Lời giải:
$2\times A=\frac{2}{1\times 3}+\frac{2}{3\times 5}+\frac{2}{5\times 7}+...+\frac{2}{19\times 21}$
$2\times A=\frac{3-1}{1\times 3}+\frac{5-3}{3\times 5}+\frac{7-5}{5\times 7}+...+\frac{21-19}{19\times 21}$
$=1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+....+\frac{1}{19}-\frac{1}{21}$
$=1-\frac{1}{21}=\frac{20}{21}$
$\Rightarrow A=\frac{20}{21}: 2= \frac{10}{21}$
= 6
nhé cảm ơn
=6
chúc bn hok tốt