câu này làm tiếp: chỉ cần tìm x tiếp rùi so sánh với điều kiện là ok nhé
\(2\times\left|1-x\right|-x+1=-3x\)
\(\Leftrightarrow2\times\left|1-x\right|=-3x+x-1\)
\(\Leftrightarrow2\times\left|1-x\right|=-2x-1\) (*)
Điều kiện : \(-2x-1\ge0\Leftrightarrow1\ge2x\Leftrightarrow2x\le1\Leftrightarrow x\le\dfrac{1}{2}\)
(*) \(\left[{}\begin{matrix}2\times1-x=-2x-1\\2\times1-x=2x-1\end{matrix}\right.\)
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Tìm x , y biết
a) 3x+2\(⋮\) 2x-1
b) x2-2x+3\(⋮\)x-1
c) \(|2x-3|+\left(y-1\right)^{2^{ }}+\left(27-1\right)^2\le0\)
Tính giá trị của các biểu thức
A =5a3b4 với a=-1;b=1
B=9a5b2với a=1;b=-1
C= ax+bx+ay+by với \(\left\{{}\begin{matrix}a+b=-2\\x+y=17\end{matrix}\right.\)
Tìm Max ; Min
A=\(|x-3|+1\)
B=\(3-|x+1|\)
C=\(\left(x-1\right)^2+\left|2y+2\right|.3\)
1: rút gọn rồi tính
\(\left(-\dfrac{72}{40}-\dfrac{144}{60}-2\dfrac{1}{3}\right)\) : \(\left(\dfrac{45}{100}-\dfrac{25}{60}+-\dfrac{75}{25}\right)\)
2: tìm x: \(3\cdot\left(4-x\right)+\left(x+2\right)\cdot\left(1+2x\right)=7\cdot\left(1+x\right)-2x\cdot\left(2-x\right)\)
3: tìm x: \(\dfrac{2\cdot\left(1+x\right)}{3}-\dfrac{5\cdot\left(2-x\right)}{6}=1\dfrac{1}{3}-\dfrac{3\cdot\left(2x+3\right)}{4}-1\dfrac{1}{2}\cdot\left(x+1\right)\)
4: cho a= \(3+3^{2^3}+3^3+3^4+...+3^{360}\)
Bài 1 Tìm \(x\)
a)\(\left(\dfrac{1}{2}\times x-3\right)\times\left(-\dfrac{1}{3}+x\right)=0\)
b)\(\dfrac{1}{2}\times x^2-\dfrac{1}{5}\times x=0\)
c)\(\dfrac{1`}{4}\times x=\dfrac{1}{16}\times x^2\)
d)\(9\times x^2=1\)
e)\(\left(x-5\right)^2=4\)
1:rút gọn
\(\dfrac{11\cdot3^{22}\cdot3^7-9^{15}}{\left(2\cdot3^{14}\right)^2}\)
2: tìm x
\(\dfrac{3\cdot\left(x-2\right)}{4}-\dfrac{2\cdot\left(1+2x\right)}{3}=1\dfrac{1}{4}-5\cdot\dfrac{\left(1+3x\right)}{6}-\dfrac{x-2}{12}\)
Tìm x biet
\(\left(2x+1\right)^3=125\)
\(1999^{2x-6}=1\)
\(x^{2002}=x\)
\(3^x+x^2=1\)
\(\left(x-1\right)^2=9\)
\(\left(2x-3\right)^2=81\)
\(x^{197}=x^2\)
\(\left(3x-14\right)^n=1\)
\(5^{2x}.55^x=625\)
Tìm x:
a,\(x^2\) - 9 = 0
b,\(\left(x-3\right)^2-25=0\)
c,\(\left(x-3\right)\left(2x-5\right)=0\)
d,\(\left(x-3\right)\cdot x-2\left(x-3\right)=0\)
e,\(3x\left(x-1\right)-5\left(1-x\right)=0\)
g,\(x^2+6x-7=0\)
h,\(2x^2+5x-7=0\)
Chứng minh rằng :
a)\(\dfrac{1}{x}\)-\(\dfrac{1}{x+a}=\dfrac{a}{x\left(x+a\right)}\)
b)\(\dfrac{1}{x\left(x+1\right)}-\dfrac{1}{\left(x+1\right)\left(x+2\right)}=\dfrac{2}{x\left(x+1\right)\left(x+2\right)}\)
c)\(\dfrac{1}{x\left(x+1\right)\left(x+2\right)}-\dfrac{1}{\left(x+1\right)\left(x+2\right)\left(x+3\right)}=\dfrac{3}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}\)
1. a) \(|\left(x-\dfrac{1}{2}\right)\left|2x-\dfrac{3}{4}\right||=2x-\dfrac{3}{4}\)
b) \(|\left|x-\dfrac{1}{2}\right|\left|2x-\dfrac{3}{4}\right||=2x-\dfrac{3}{4}\)
2. Cho x + y = 3. Tìm gtnn của biểu thức:
\(\left|x+1\right|+\left|y-2\right|\)
Giúp mình vs m.n ơi 
tính:
\(\dfrac{2}{5}x\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}x\dfrac{1}{3}\)
2)\(\left(3\dfrac{1}{3}+2,5\right):\left(3\dfrac{1}{6}-4\dfrac{1}{5}\right)-\dfrac{11}{31}\)
3)\(\left[6+\left(\dfrac{1}{2^{ }}\right)^3-\left|-\dfrac{1}{2}\right|\right]:\dfrac{3}{12}\)
4)\(\dfrac{18}{37}+\dfrac{8}{24}+\dfrac{19}{37}-1\dfrac{23}{24}+\dfrac{2}{3}\)
5) \(\left(-2\right)^3x\left(\dfrac{3}{4}-0,25\right):\left(2\dfrac{1}{4}-1\dfrac{1}{6}\right)\)
6)\(\left(\dfrac{2}{5}\right)^2+5\dfrac{1}{2}x\left(45-2\right)+\dfrac{23}{-4}\)
7)\(\dfrac{4}{9}-19\dfrac{1}{3}-\dfrac{4}{9}x39\dfrac{1}{3}\)
8)\(\left(-\dfrac{1}{2}\right)^2:\dfrac{1}{4}-2x\left(-\dfrac{1}{2}\right)^2\)
9)\(125\%x\left(-\dfrac{1}{2}\right)^3:\left(1\dfrac{5}{16}-1,5\right)+2008^0\)
giúp mình nha mai mình học rùi 
