BT1: Tìm x, biết:
5) \(\text{|}x+\dfrac{1}{3}\text{|}+\text{|}x+\dfrac{1}{5}\text{|}+\text{|}x+\dfrac{1}{15}\text{|}=4x\)
\(\left|x+\dfrac{1}{3}\right|+\left|x+\dfrac{1}{5}\right|+\left|x+\dfrac{1}{15}\right|=4x\)
Mà \(\left\{{}\begin{matrix}\left|x+\dfrac{1}{3}\right|\ge0\\\left|x+\dfrac{1}{5}\right|\ge0\\\left|x+\dfrac{1}{15}\right|\ge0\end{matrix}\right.\)
\(\Leftrightarrow\left|x+\dfrac{1}{3}\right|+\left|x+\dfrac{1}{5}\right|+\left|x+\dfrac{1}{15}\right|\ge0\)
\(\Leftrightarrow4x\ge0\)
\(\Leftrightarrow x+\dfrac{1}{3}+x+\dfrac{1}{5}+x+\dfrac{1}{15}=4x\)
\(\Leftrightarrow3x+1=4x\)
\(\Leftrightarrow x=1\)
Vậy ..
1) \(\dfrac{1}{3}-\left(1\dfrac{1}{2}-x\right)=0,3\)
-1,75-(\(\dfrac{-1}{9}\)-\(2\dfrac{1}{18}\))
a)\(-\dfrac{3}{4}.31\dfrac{11}{23}-0,75.8\dfrac{12}{23}\)
A=( 3 +\(\dfrac{1}{2}\)-\(\dfrac{2}{3}\)) - ( 2-\(\dfrac{2}{3}\)+\(\dfrac{5}{2}\)) - ( 5-\(\dfrac{5}{2}\)+\(\dfrac{4}{3}\))
Tính giá trị của A theo 2 cách
ai nhanh mình tick
2. Tính nhanh
a) A=(\(\dfrac{1}{2}\)- \(\dfrac{7}{13}\)-\(\dfrac{1}{3}\))+(\(\dfrac{-6}{13}\) +\(\dfrac{1}{2}\)+1\(\dfrac{1}{3}\))
b) B = (-1\(\dfrac{1}{2}\):\(\dfrac{3}{-4}\)) .(-4\(\dfrac{1}{2}\)) -\(\dfrac{1}{4}\)
Giúp mình với
Tìm x, biết a. x + \(\dfrac{3}{10}=\dfrac{-2}{15}\) b. \(\dfrac{-11}{12}x+0,25=\dfrac{5}{6}\) c. x + (x+1)+(x+2)+==+(x+2002)=2004
Thực hiện phép tính a. \(\dfrac{-1}{24}-\left\{\dfrac{1}{4}-\left(\dfrac{1}{2}-\dfrac{7}{8}\right)\right\}\) b.\(\left(8\dfrac{5}{11}+3\dfrac{5}{8}\right)-3\dfrac{5}{11}\)
c.\(\dfrac{4}{9}:\left(\dfrac{-1}{7}\right)+6\dfrac{5}{9}:\left(\dfrac{-1}{7}\right)\)
d. \(\left(\dfrac{-1}{5}+\dfrac{3}{7}\right):\dfrac{2}{11}+\left(\dfrac{-4}{5}+\dfrac{4}{7}\right):\dfrac{2}{11}\) M.n giúp mk nha
2. Tính
a) (\(\dfrac{3}{7}\))\(^{21}\) : (\(\dfrac{9}{49}\))\(^6\)
b) 3- (\(-\dfrac{6}{7}\))\(^0\) + (\(\dfrac{1}{2}\))\(^2\) : 2
Giúp mk vs
1. Tìm x \(\in\) Q, biết
a) (x-\(\dfrac{1}{3}\))\(^2\) = 0
b) (x+\(\dfrac{1}{2}\))\(^2\) = \(\dfrac{1}{16}\)
c) (2x-1)\(^3\) = 8
2) Tìm x \in∈ N*
a)27<3x<3.81
b)415.915<2x.3x<1816.216
c)(2x-1)6=(2x-1)8
giúp mình nha, mình đang cần gấp
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