bài 2 tìm x

a,\(\frac{-2}{3}.x+\frac{1}{5}=\frac{3}{10}\)

b,\(\left|x\right|-\frac{3}{4}=\frac{5}{3}\)

c,\(\frac{2}{3}.x-\frac{1}{2}=\frac{1}{10}\)

d,\(\frac{3}{5}+\frac{4}{9}:x=\frac{2}{3}\)

e,\(\left|x+75\%\right|=2\frac{1}{5}\)

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

k,\(\frac{4}{7}.x-\frac{2}{3}=\frac{1}{5}\)

l,\(\frac{2}{3}.x-\frac{3}{2}.x=\frac{5}{12}\)

m,\(\left|2.x-\frac{1}{3}\right|+\frac{5}{6}=1\)

n,\(\frac{1}{3}-\frac{7}{8}.x=\frac{1}{3}\)

11,\(\frac{x+2}{5}=\frac{7}{12}-1\frac{1}{4}\)

12,\(\left(2\frac{4}{5}.x-50\right):\frac{2}{3}=51\)

13,\(\frac{2}{5}+\frac{3}{5}.\left(3.x-3,7\right)=-\frac{53}{10}\)

14,\(\frac{7}{9}:\left(2+\frac{3}{4}.x\right)+\frac{5}{9}=\frac{23}{27}\)

tìm x\(\in\) Q,biết: 

a,\(\frac{x}{2}\left(\frac{3x}{5}\right)-\frac{13}{5}=-\left(\frac{7}{5}+\frac{7}{10}x\right)\)

b,\(\frac{2x-3}{3}+\frac{-3}{2}=\frac{5-3x}{6}-\frac{1}{3}\)

c,\(\left(\frac{3}{2}-\frac{2}{-5}\right):x-\frac{1}{2}=\frac{3}{2}\)

d,\(\frac{13}{x-1}+\frac{5}{2x+2}-\frac{6}{3x-3}\)

e,\(\left(\frac{3}{2}-\frac{5}{11}-\frac{3}{13}\right)\left(2x-2\right)=\left(\frac{-3}{4}+\frac{5}{22}+\frac{3}{26}\right)\)

Ai bt câu nào làm câu đấy nhé ! Làm hết cũng đc nhé!

Tính hợp lý (nếu được)

\(a\) \(19\frac{5}{8}\)\(:\)\(1\frac{5}{7}\)\(-\) \(15\frac{5}{8}\) \(:\) \(\frac{12}{17}\)\(-\)\(1\frac{1}{3}\)

\(b\) \(\frac{2}{5}\)\(.\)\(\frac{1}{3}\)\(-\) \(\frac{2}{15}\)\(:\) \(\frac{1}{5}\)\(+\) \(\frac{3}{5}\)\(.\) \(\frac{1}{3}\)

\(c\)\(\left(3\frac{1}{3}+2,5\right):\left(3\frac{1}{6}-4\frac{1}{5}\right)-\frac{11}{31}\)

\(f\)\(\left(-2\right)^3.\left(\frac{3}{4}-0,25\right):\left(2\frac{1}{4}-1\frac{1}{6}\right)\)

\(g\)\(\left(\frac{2}{5}\right)^2+5\frac{1}{2}.\left(4,5-2\right)+\frac{2^3}{\left(-4\right)}\)

\(h\)\(\frac{4}{9}.19\frac{1}{3}-\frac{4}{9}.39\frac{1}{3}\)

\(k\)\(125\%.\left(\frac{-1}{2}\right)^2:\left(1\frac{5}{16}-1,5\right)+2008^0\)

\(m\)\(F=\frac{1}{18}+\frac{1}{54}+\frac{1}{108}+...+\frac{1}{990}\)

Làm bao nhiêu cũng được nha, càng nhiều càng tốt

Bài 1: Tìm x biết:

a. \(\frac{5}{1.6}+\frac{5}{6.11}+...+\frac{5}{\left(5x+1\right)\left(5x+6\right)}=\frac{2010}{2011}\)

b. \(\frac{7}{x}+\frac{4}{5.9}+\frac{4}{9.13}+\frac{4}{13.17}+..+\frac{4}{41.45}=\frac{29}{45}\)

c. \(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{1}{x\left(x+2\right)}:2\)

d. (x-20) . \(\frac{\frac{1}{2}+\frac{1}{3}+..+\frac{1}{2000}}{\frac{1}{199}+\frac{2}{198}+\frac{3}{197}+...+\frac{198}{2}+\frac{199}{1}}=\frac{1}{2000}\)

Bài 2:

 \(\frac{a}{n\left(n+a\right)}=\frac{1}{n}-\frac{1}{n+a}\left(n,a\right)\in Nsao\)

Bài 3:

a)\(\frac{3}{x}+\frac{y}{3}=\frac{5}{6}\)

b) \(\frac{x}{3}-\frac{4}{y}=\frac{1}{5}\)

c) \(\frac{x}{2}+\frac{y}{3}=\frac{x+y}{2+3}\)

d) \(\frac{x-1}{9}+\frac{1}{3}=\frac{1}{y+2}\)

1. tinh` giá trị biểu thức ( tính nhanh nếu có thế )

\(a)\frac{-6}{11}.\frac{5}{13}+\frac{-6}{11}.\frac{8}{13}-\left(\frac{-2}{5}\right)^0\) \(b)\left(2\frac{2}{3}+3\frac{1}{2}\right);\left(4\frac{3}{4}-2\frac{1}{6}\right)+\frac{19}{31}\) \(c)2,4:\left(-2\right)^3+\left(3-\frac{9}{11}\right).1\frac{3}{8}\)

\(d)\left(-\frac{3}{4}\right)^2:\frac{-3}{8}+\frac{1}{2}-\frac{3}{4}-\left(\frac{-78}{57}\right)^0\)

2. tìm x

\(a)x+\frac{-1}{5}=\left(-\frac{3}{4^{ }}\right)^2\) \(b)\left|\frac{5}{2}x+\frac{2}{3}\right|-\frac{1}{4}=0\) \(c)\frac{2}{3}x-\frac{1}{2}=\frac{5}{12}+\frac{1}{2}x\) \(d)\left(x-\frac{1}{4}\right)^4=\frac{1}{81}\)

\(e)4x+3\frac{1}{4}=x-\frac{1}{4}\) \(g)\left(x-\frac{1}{3}\right)^3=\frac{1}{27}\)

a) \(\frac{2}{5}+\left(-\frac{4}{3}\right)+\left(-\frac{1}{2}\right)\)
b) \(\frac{5}{8}-\left(-\frac{2}{5}-\frac{3}{10}\right)\)
c) \(\frac{1}{3}-\left[\left(-\frac{5}{4}\right)-\left(\frac{1}{4}+\frac{3}{8}\right)\right]\)
d) \(\frac{2}{3}-4.\left(\frac{1}{2}+\frac{3}{4}\right)\)
e) \(\left(-\frac{1}{3}+\frac{5}{6}\right).11-7\)
f) \(\left(-\frac{5}{9}\right).\frac{3}{11}+\left(-\frac{13}{18}\right).\frac{3}{11}\)

Chứng minh rằng:

a)\(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{2010^2}\)<1

b)\(\frac{1}{2}+\frac{2}{2^2}+\frac{3}{2^3}+\frac{4}{2^4}+...+\frac{100}{2^{100}}\)<2

c)\(\frac{1}{3}+\frac{2}{3^2}+\frac{3}{3^3}+...+\frac{100}{3^{100}}\)<\(\frac{3}{4}\)

d)\(\frac{1}{3^3}+\frac{1}{4^3}+\frac{1}{5^3}+...+\frac{1}{n^3}\)<\(\frac{1}{12}\)\(\left(n\in N;n\ge3\right)\)

e)\(\frac{3}{4}+\frac{5}{36}+\frac{7}{144}+...+\frac{2n+1}{n^2\left(n+1\right)^2}\)<1 (n nguyên dương)

g)\(\frac{1}{31}+\frac{1}{32}+\frac{1}{33}+...+\frac{1}{2048}\)>3

h)\(\left(\frac{2}{1}\right)\left(\frac{4}{3}\right)\left(\frac{6}{5}\right)...\left(\frac{200}{199}\right)\)