bài 1: Tìm x,y biết rằng:

                                  \(x+(-\frac{31}{12})^2=\left(\frac{49}{12}\right)^2-x=y^2\) 

bài 2: tìm x biết:

a.\(5^x.\left(5^3\right)^2=625\)   b.\(\left(\frac{12}{25}\right)^x=\left(\frac{5}{3}\right)^{-2}-\left(-\frac{3}{5}\right)^4\)     c.\(\left(-\frac{3}{4}\right)^{3x-1}=\frac{256}{81}\)   

d.\(172x^2-7^9:98^3=2^{-3}\)

Bài 3: Tìm x \(\varepsilon\)N biết:

a.\(8< 2^x\le2^9\times2^{-5}\)     b.\(27< 81^3:3^x< 243\)     \(\left(\frac{2}{5}\right)^x>\left(\frac{5}{2}\right)^{-3}\times\left(-\frac{2}{5}\right)^2\)c.

Bài 4: Tính hợp lý

a) \(A=\left(\left|\frac{-3}{4}\right|+\left|\frac{-2}{5}\right|\right):\frac{3}{7}+\left(\frac{-3}{5}+\left|\frac{-1}{4}\right|\right):\frac{3}{7}\)

b) \(B=2\frac{5}{23}-\left(\frac{-7}{9}\right)-\left|\frac{-5}{23}\right|+\frac{12}{9}+\left|-0,75\right|\)

Bài 5 : Tìm x :

\(\frac{11}{12}-\left(\frac{2}{5}+x\right)=\left|\frac{-2}{3}\right|\)

b) \(\left|x\right|:\left(\frac{1}{9}-\frac{2}{5}\right)=\frac{-1}{2}\)

c) \(\left(x-\frac{1}{5}\right).\left(1\frac{3}{5}+2x\right)=0\)

Bài 4.1: Tìm x, biết

a) \(4\left|3x-1\right|+\left|x\right|-2\left|x-5\right|+7\left|x-3\right|=12\)

b) \(3\left|x+4\right|-\left|2x+1\right|-5\left|x+3\right|+\left|x-9\right|=5\)

c) \(\left|2\frac{1}{5}-x\right|+\left|x-\frac{1}{5}\right|+8\frac{1}{5}=1,2\)

d) \(2\left|x+3\frac{1}{2}\right|+\left|x\right|-3\frac{1}{2}=\left|2\frac{1}{5}-x\right|\)

Tìm x,biết

a, \(\frac{3}{\left(x+2\right)\left(x+5\right)}+\frac{5}{\left(x+5\right)\left(x+10\right)}+\frac{7}{\left(x+10\right)\left(x+17\right)}=\frac{x}{\left(x+2\right)\left(x+17\right)}\)

Với x ∉ -2,-5,-10,-17

b,\(\frac{2}{\left(x-1\right)\left(x-3\right)}+\frac{5}{\left(x-3\right)\left(x-8\right)}+\frac{12}{\left(x-8\right)\left(x-20\right)}-\frac{1}{x-20}=\frac{-3}{4}\)

Với x∉1,3,8,20

c,\(\frac{x-1}{2009}+\frac{x-2}{2008}=\frac{x-3}{2007}+\frac{x-4}{2006}\)

Tìm \(x,\) biết:

a) \(4\left|3x-1\right|+\left|x\right|-2\left|x-5\right|+7\left|x-3\right|=12\)

b) \(3\left|x+4\right|-\left|2x+1\right|-5\left|x+3\right|+\left|x+9\right|=5\)

c) \( \left|2\frac{1}{5}-x\right|+\left|x-\frac{1}{5}\right|+8\frac{1}{5}=1,2\)

d) \(2\left|x+3\frac{1}{2}\right|+\left|x\right|-3\frac{1}{2}=\left|2\frac{1}{5}-x\right|\)

TÌM x BIẾT:

a,\(\frac{3}{\left(x+2\right)\left(x+5\right)}+\frac{5}{\left(x+5\right)\left(x+10\right)}+\frac{7}{\left(x+10\right)\left(x+17\right)}=\frac{x}{\left(x+2\right)\left(x+17\right)}\)

với x\(\notin\){-2;-5;-10;-17}

b,\(\frac{2}{\left(x-1\right)\left(x-3\right)}+\frac{5}{\left(x-3\right)\left(x-8\right)}+\frac{12}{\left(x-8\right)\left(x-20\right)}-\frac{1}{x-20}=\frac{-3}{4}\)

với x\(\notin\){1;3;8;20}

c, TÌM X BIẾT:

\(\frac{x-1}{2009}+\frac{x-2}{2008}=\frac{x-3}{2007}+\frac{x-4}{2006}\)

GIÚP MÌNH CHÚT NHA MÌNH CẦN NGAY. THANKS!