Tìm x, biết:
\(x^2:\left(-1\frac{1}{9}\right)=-2,5\)
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a)
( 4x - 9 ) ( 2,5 + (-7/3) . x ) = 0
\(\Rightarrow\orbr{\begin{cases}4x-9=0\\2,5+\frac{-7}{3}x=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{9}{4}\\x=\frac{15}{14}\end{cases}}\)
P/s: đợi xíu làm câu b
b) \(\frac{1}{x\left(x+1\right)}\cdot\frac{1}{\left(x+1\right)\left(x+2\right)}\cdot\frac{1}{\left(x+2\right)\left(x+3\right)}-\frac{1}{x}=\frac{1}{2015}\)
\(\frac{1}{x}-\frac{1}{x+1}+\frac{1}{x+1}-\frac{1}{x+2}+\frac{1}{x+2}-\frac{1}{x+3}-\frac{1}{x}=\frac{1}{2015}\)
\(\frac{-1}{x+3}=\frac{1}{2015}\)
\(\Leftrightarrow x+3=-2015\)
\(\Leftrightarrow x=-2018\)
Vậy,.........
a ) \(\left(\frac{2}{5}-x\right):1\frac{1}{3}+\frac{1}{2}=-4\)
\(\left(\frac{2}{5}-x\right):\frac{4}{3}+\frac{1}{2}=-4\)
\(\left(\frac{2}{5}-x\right):\frac{4}{3}=-4-\frac{1}{2}\)
\(\left(\frac{2}{5}-x\right):\frac{4}{3}=-\frac{9}{2}\)
\(\frac{2}{5}-x=-\frac{9}{2}.\frac{4}{3}\)
\(\frac{2}{5}-x=-3\)
\(x=\frac{2}{5}-\left(-3\right)\)
\(x=\frac{2}{5}+3\)
\(x=\frac{3}{5}-\frac{15}{5}\)
\(x=-\frac{12}{5}\)
Vay \(x=-\frac{12}{5}\)
b ) \(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\left(1+\frac{2}{5}+\frac{2}{3}\right)=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\left(\frac{15}{15}+\frac{6}{15}+\frac{10}{15}\right)=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\left(\frac{15+6+10}{15}\right)=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right):\frac{31}{15}=-\frac{5}{4}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right)=-\frac{5}{4}.\frac{31}{15}\)
\(\left(-3+\frac{3}{x}-\frac{1}{3}\right)=-\frac{1}{4}.\frac{31}{3}\)
\(-3+\frac{3}{x}-\frac{1}{3}=-\frac{31}{12}\)
\(-3+\frac{3}{x}=-\frac{31}{12}+\frac{1}{2}\)
\(-3+\frac{3}{x}=-\frac{31}{12}+\frac{6}{12}\)
\(-3+\frac{3}{x}=\frac{-25}{12}\)
\(\frac{3}{x}=\frac{-25}{12}+3\)
\(\frac{3}{x}=\frac{-25}{12}+\frac{36}{12}\)
\(\frac{3}{x}=\frac{5}{6}\)
\(\frac{18}{6x}=\frac{5x}{6x}\)
Đèn dây , bạn tự làm tiếp nhé , de rồi chứ
Đoạn đó ( dưới ) :
\(\Rightarrow\left[\begin{array}{nghiempt}\frac{1}{4}x=2\\\frac{1}{4}x=-2\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}x=8\\x=-8\end{array}\right.\)
:)
Giải :
\(\frac{1}{4}\left|x\right|-2,5=-\frac{1}{2}\)
\(\Rightarrow\frac{1}{4}\left|x\right|=2\)
\(\Rightarrow\left[\begin{array}{nghiempt}\frac{1}{4}.x=2\\\frac{1}{4}.x=-2\end{cases}\Rightarrow\left[\begin{array}{nghiempt}x=8\\x=-8\end{array}\right.}\)
3.
a) \(\left|x\right|=2,1\Leftrightarrow\left[\begin{array}{nghiempt}x=2,1\\x=-2,1\end{array}\right.\)
b)\(\left|x\right|=\frac{17}{9}\Leftrightarrow x=-\frac{17}{9}\) (vì x/<0)
c) \(\left|x\right|=1\frac{2}{5}\Leftrightarrow\left|x\right|=\frac{7}{5}\Leftrightarrow\left[\begin{array}{nghiempt}x=\frac{7}{5}\\x=-\frac{7}{5}\end{array}\right.\)
d) \(\left|x\right|=0,35\Leftrightarrow x=0,35\) (Vì x>0)
2.
a) \(\left|x-1,7\right|=2,3\)
\(\Leftrightarrow\begin{cases}x\ge1,7\\x-1,7=2,3\end{cases}\) hoặc \(\begin{cases}x< 1,7\\1,7-x=2,3\end{cases}\)
\(\Leftrightarrow\begin{cases}x\ge1,7\\x=4\left(tm\right)\end{cases}\) hoặc \(\begin{cases}x< 1,7\\x=-0,6\left(tm\right)\end{cases}\)
Vậy x={4;-0,6}
b) đề thiếu
a) |- 2,5| = 2,5 b) |- 2,5| = - 2,5 c) |- 2,5| = - |- 2,5|
>.<
\(\left(-\frac{28}{19}\right)\times\left(-\frac{38}{14}\right)=\frac{14\times2\times19\times2}{19\times14}=4\)
>.<
\(\left(-\frac{21}{16}\right)\times\left(-\frac{24}{7}\right)=\frac{7\times3\times8\times3}{8\times2\times7}=\frac{9}{2}\)
>.<
\(\left(-\frac{12}{17}\right)\times\left(-\frac{34}{9}\right)=\frac{3\times4\times17\times2}{17\times3\times3}=\frac{8}{3}\)
>.<
\(\left|x\right|=2,1\)
\(x=\pm2,1\)
>.<
\(\left|x\right|=\frac{17}{9}\)
\(x=\pm\frac{17}{9}\)
x < 0
\(x=-\frac{17}{9}\)
>.<
\(\left|x\right|=1^2_5\)
\(x=\pm\frac{7}{5}\)
>.<
\(\left|x\right|=0,35\)
\(x=\pm0,35\)
x > 0
x = 0,35
>.<
\(\left|x-1,7\right|=2,3\)
\(x-1,7=\pm2,3\)
Th1:
x - 1,7 = 2,3
x = 2,3 + 1,7
x = 4
Th2:
x - 1,7 = - 2,3
x = - 2,3 + 1,7
x = - 0,6
>.<
\(\left|x+\frac{3}{4}\right|-\frac{1}{3}=0\)
\(\left|x+\frac{3}{4}\right|=\frac{1}{3}\)
\(x+\frac{3}{4}=\pm\frac{1}{3}\)
Th1:
x + 3/4 = 1/3
x = 1/3 - 3/4
x = \(-\frac{5}{12}\)
Th2:
\(x+\frac{3}{4}=-\frac{1}{3}\)
\(x=-\frac{1}{3}-\frac{3}{4}\)
\(x=-\frac{13}{12}\)
1)\(\frac{x+1}{2}+\frac{x+1}{3}+\frac{x+1}{4}=\frac{x+1}{5}+\frac{x+1}{6}\)
\(\Leftrightarrow\frac{x+1}{2}+\frac{x+1}{3}+\frac{x+1}{4}-\frac{x+1}{5}-\frac{x+1}{6}=0\)
\(\Leftrightarrow\left(x+1\right)\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}-\frac{1}{5}-\frac{1}{6}\right)=0\)
\(\Leftrightarrow\left(x+1\right)=0\).Do \(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}-\frac{1}{5}-\frac{1}{6}\ne0\)
\(\Leftrightarrow x=-1\)
|2,5-x|=1,3
\(\orbr{\begin{cases}2,5-x=1,3\\2,5-x=-1,3\end{cases}}\Rightarrow\orbr{\begin{cases}x=1,2\\x=3,8\end{cases}}\)
Vậy x=1,2 hoặc x=3,8
|x-1,5|+|2,5-x|=0
\(\Rightarrow\hept{\begin{cases}VT:x-1,5=0\\VP:2,5-x=0\end{cases}}\Rightarrow\hept{\begin{cases}x=1,5\\x=2,5\end{cases}}\)
Vậy x của VT là 1,5 và x của VP là 2,5
\(\left(x-\frac{1}{2}\right)^2=0\)
\(\Rightarrow x-\frac{1}{2}=0\)
x=\(0+\frac{1}{2}\)
x=\(\frac{1}{2}\)
(x-2)2=1
=> x-2=1
x=1+2
x=3
=> x-2=-1
x=(-1)+2
x=1
a, / 2,5 - x / = 1,3
Với 2,5 - x > hoặc = 0 => 2, 5 - x = 1,3
=> x = 1, 2
Với 2,5 - x < hoặc = 0 => - ( 2,5 - x ) = 1,3
=> - 2,5 + x = 1,3
=> x = 3,8
Vậy x thuộc tập hợp 1,2 ; 3,8
p/s: > hoặc = 0, < hoặc = 0 , thuộc tập hợp bạn ghi kí hiệu nha
\(x^2:\left(-1\frac{1}{9}\right)=-2,5\)
\(x^2=-2,5.\left(-1\frac{1}{9}\right)\)
\(x^2=-2,5.\left(-\frac{10}{9}\right)=-\frac{25}{10}.\left(-\frac{10}{9}\right)\)
\(x^2=\frac{25}{9}\)
\(x^2=\frac{25}{9}\)
\(\orbr{\begin{cases}x=\frac{5}{3}\\x=-\frac{5}{3}\end{cases}}\)