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HD
4
XO
21 tháng 7 2020
\(\frac{x+12}{7}+\frac{x+4}{15}+\frac{x+6}{13}=\frac{x+8}{11}+\frac{x+10}{9}+\frac{x+12}{7}\)
=>\(\left(\frac{x+12}{7}+1\right)+\left(\frac{x+4}{15}+1\right)+\left(\frac{x+6}{13}+1\right)=\left(\frac{x+8}{11}+1\right)+\left(\frac{x+10}{9}+1\right)+\left(\frac{x+12}{7}+1\right)\)
=> \(\frac{x+19}{7}+\frac{x+19}{15}+\frac{x+19}{13}=\frac{x+19}{11}+\frac{x+19}{9}+\frac{x+19}{7}\)
=> \(\frac{x+19}{7}+\frac{x+19}{15}+\frac{x+19}{13}-\frac{x+19}{11}-\frac{x+19}{9}-\frac{x+19}{7}=0\)
\(\Rightarrow\left(x+19\right)\left(\frac{1}{7}+\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}-\frac{1}{7}\right)=0\)
=> x + 19 = 0 Vì \(\frac{1}{7}+\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}-\frac{1}{7}\ne0\)
=> x = - 19
21 tháng 7 2020
Bài làm:
Ta có: \(\frac{x+12}{7}+\frac{x+4}{15}+\frac{x+6}{13}=\frac{x+8}{11}+\frac{x+10}{9}+\frac{x+12}{7}\)
\(\Leftrightarrow\left(\frac{x+12}{7}+1\right)+\left(\frac{x+4}{15}+1\right)+\left(\frac{x+6}{13}+1\right)-\left(\frac{x+8}{11}+1\right)-\left(\frac{x+10}{9}+1\right)-\left(\frac{x+12}{7}+1\right)=0\)
\(\Leftrightarrow\frac{x+19}{7}+\frac{x+19}{15}+\frac{x+19}{13}-\frac{x+19}{11}-\frac{x+19}{9}-\frac{x+19}{7}=0\)
\(\Leftrightarrow\left(x+19\right)\left(\frac{1}{7}+\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}-\frac{1}{7}\right)=0\)
\(\Leftrightarrow\left(x+19\right)\left(\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}\right)=0\)
Mà \(\hept{\begin{cases}\frac{1}{15}< \frac{1}{11}\\\frac{1}{13}< \frac{1}{9}\end{cases}\Rightarrow}\frac{1}{15}+\frac{1}{13}-\frac{1}{11}-\frac{1}{9}< 0\)
\(\Rightarrow x+19=0\)
\(\Rightarrow x=-19\)
PH
16 tháng 5 2022
a.-1,75-(-\(\dfrac{1}{9}\)-2\(\dfrac{1}{8}\))
-1,75-\(\dfrac{1}{9}+\dfrac{17}{8}\)
\(-\dfrac{7}{4}-\dfrac{1}{9}+\dfrac{17}{8}\)
\(\dfrac{-126}{72}-\dfrac{8}{72}+\dfrac{153}{72}\)
=\(\dfrac{19}{72}\)
PH
16 tháng 5 2022
b.\(\dfrac{-1}{12}-\left(2\dfrac{5}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\left(\dfrac{21}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\dfrac{21}{8}+\dfrac{1}{3}\)
\(\dfrac{-2}{24}-\dfrac{63}{24}+\dfrac{64}{24}\)
=\(\dfrac{-1}{24}\)
7 tháng 8 2019
8 ) - 12 = 1
\(|x+12|=13\)
\(\Rightarrow\orbr{\begin{cases}x+12=13\\x+12=-13\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=1\\x=-25\end{cases}}\)
Vậy \(x\in\left\{1;-25\right\}\)
9) 135 -\(|9-x|=35\)
\(|9-x|=135-35\)
\(|9-x|=100\)
\(\Rightarrow\orbr{\begin{cases}9-x=100\\9-x=-100\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-91\\x=109\end{cases}}\) Vậy x\(\in\left\{-91;109\right\}\) 10) 17+x-(352-400)=-32 17+x-352+400=-32 17+x-352 =(-32) - 400 17+x-352 =-432 17+x =(-432) + 352 17+x =-80 x =(-80) - 17 x =-97 Vậy x =-97 11) 2130 - (x+136) + 72 =-64 2130 - (x+136) =(-64) -72 2130 - (x+136) =-136 (x +136) = 2130 -(-136) x+136 =2266 x =2266 - 136 x =2130 Vậy x=2130 do sap an cơm nên chiều mình sẽ giải tiếp nha! sorryy
7 tháng 8 2019
12) (x-2) - (-8) = -137
(x-2) +8 =-137
(x-2) =(-137) - 8
x-2 =-145
Vậy x=-145
13) 10-\(|x+3|=-4.\left(-10\right)\) 10- \(|x+3|=40\) \(|x+3|=\) 40+10 \(|x+3|=50\)
\(\Rightarrow\orbr{\begin{cases}x+3=50\\x+3=-50\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=50-3\\x=\left(-50\right)-3\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=20\\x=-53\end{cases}}\)
Vậy x\(\in\left\{20;-53\right\}\)
\(\dfrac{x+2}{17}+\dfrac{x+4}{15}+\dfrac{x+6}{13}=\dfrac{x+8}{11}+\dfrac{x+10}{9}+\dfrac{x+12}{7}\)
\(\Leftrightarrow\dfrac{x+2}{17}+1+\dfrac{x+4}{15}+1+\dfrac{x+6}{13}=\dfrac{x+8}{11}+1+\dfrac{x+10}{9}+1+\dfrac{x+12}{7}+1\)
\(\Leftrightarrow\dfrac{x+19}{17}+\dfrac{x+19}{15}+\dfrac{x+19}{13}=\dfrac{x+19}{11}+\dfrac{x+19}{9}+\dfrac{x+19}{7}\)
\(\Leftrightarrow\left(x+19\right)\left(\dfrac{1}{17}+\dfrac{1}{15}+\dfrac{1}{13}-\dfrac{1}{11}-\dfrac{1}{9}-\dfrac{1}{7}\right)=0\)
\(\Leftrightarrow x+19=0\)
\(\Leftrightarrow x=-19\)
Vậy ...
(x+2)/17+(x+4)/15+(x+6)/13-(x+8)/11-(x+10)/9 + (x+12)/7=0
Cộng 1 vào các hạng tử ta được:
(x+19)/17+(x+19)/15+(x+19)/13-(x+19)/11-(x+19)/9-(x+19)/7=0
=> (x+19)(1/17+1/15+1/13-1/11-1/9-1/7)=0
=>x+19=0
=>x=-19
Vậy x= -19
Chúc bạn học tốt!!!