giúp mình nha (. là nhân nhé)

1.thực hiện phép tính

a)(-\(\dfrac{2}{3}\)).\(\dfrac{3}{11}\)-(\(\dfrac{4}{3}\))\(^2\).\(\dfrac{3}{11}\)

b)(-1\(\dfrac{3}{4}\))\(^2\)-(\(\dfrac{1}{2}\))\(^4\)

c)(-\(\dfrac{1}{3}\))\(_7\).3\(^7\)

d)(5-\(\dfrac{1}{5}\)+\(\dfrac{1}{6}\))-(4-\(\dfrac{1}{5}\)+\(\dfrac{5}{6}\))-(3-\(\dfrac{1}{2}\)-\(\dfrac{1}{6}\))

2.tìm x

a)/x+\(\dfrac{3}{4}\)/-\(\dfrac{1}{2}\)=0

b)(x-1)\(^2\)-1=(-2)\(^3\)

c)1-(3-x)\(^3\)=(-13).2

d)(2-x)\(^4\)-17=3\(^2\).(-2)

1/ Cho A = 1 + 2\(^1\)+ 2\(^2\)+ 2\(^3\)+ 2\(^4\)+ 2\(^5\). Tính 2A. Chứng minh A = 2\(^6\)- 1

2/ Cho A = 1 + 2\(^1\)+ 2\(^2\)+ ............+ 2\(^{2006}\). Tính 2A. Chứng minh A = 2\(^{2006}\)-  1

3/ Cho A = 1 + 3 + 3\(^2\)+ 3\(^3\)+ .....3\(^7\). Tính 3A. Chứng minh A = \(\frac{3^8-1}{2}\)

A=\(\frac{1}{2}\)+\(\frac{1}{2^2}\)+\(\frac{1}{2^3}\)+....+\(\frac{1}{2^9}\)

B=\(\frac{1}{4}\)+\(\frac{1}{12}\)+\(\frac{1}{30}\)+....+\(\frac{1}{972}\)

C= 1+\(\frac{1}{2}\)(1+2)+\(\frac{1}{3}\)(1+2+3)+....+\(\frac{1}{20}\)(1+2+3+....+20)

 LÀM ƠN GIÚP MÌNH NHA ;^;

Chứng minh:

a) 1+ 2+ 3+ ...+( n- 1)+ n= \(\frac{n\left(n+1\right)}{2}\).

b) 1\(^2\)+ 2\(^2\)+ 3\(^2\)+...+( n- 1)\(^2\)+ n\(^2\)= \(\frac{n\left(n+1\right)\left(2n+1\right)}{6}\).

c) 1\(^3\)+ 2\(^3\)+ 3\(^3\)+...+( n- 1)\(^3\)+ n\(^3\)= \(\left[\frac{n\left(n+1\right)}{2}\right]^2\).

tìm x biết

a) \(\dfrac{2}{3}\): x - \(\dfrac{5}{6}\)= 1\(\dfrac{1}{2}\)

b) (\(\dfrac{5}{6}\) . x + \(\dfrac{2}{3}\)) : (\(\dfrac{2}{5}\) +\(1\dfrac{1}{3}\) )\(\dfrac{4}{9}\)

c) \(|\)x - \(\dfrac{4}{3}\)\(|\) - \(\dfrac{5}{6}\) = \(\dfrac{3}{5}\) . \(1\dfrac{1}{2}\)

d) \(|\)2x + \(\dfrac{1}{2}\)\(|\) - \(\dfrac{3}{4}\)=\(3\dfrac{1}{2}\)

e) \(|\dfrac{3}{2}\)x - \(\dfrac{5}{6}|\)+ \(\dfrac{12}{5}\)= \(1\dfrac{1}{2}\)

bài 1

a,\(\frac{x}{5}\)=\(\frac{2}{3}\)

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

c,\(\frac{x}{5}\)+\(\frac{1}{2}\)=\(\frac{6}{10}\)

d,\(\frac{x+3}{15}\)=\(\frac{1}{3}\)

e,\(\frac{x-12}{4}\)=\(\frac{1}{2}\)

h,\(\frac{4}{5}\)+x=\(\frac{2}{3}\)

i,\(\frac{3}{4}\)-x=\(\frac{1}{3}\)

k,\(\frac{-5}{6}\)-x=\(\frac{2}{3}\)

l,x-\(\frac{5}{9}\)=\(\frac{-2}{3}\)

m,\(\frac{1}{2}\)x+\(\frac{1}{2}\)=\(\frac{5}{2}\)

n,\(\frac{-2}{3}\)-\(\frac{1}{3}\)(2x-5)=\(\frac{3}{2}\)

p,(3x-1)(\(-\frac{1}{2}\)x+5)=0

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

s,\(\frac{1}{2}\)-\(\frac{2}{3}\)x=\(\frac{7}{12}\)

t,\(\frac{3}{4}\)x+\(\frac{1}{5}\)=\(\frac{1}{6}\)

u,\(\frac{3}{8}\)-\(\frac{1}{6}\)x=\(\frac{1}{4}\)

mn ơi'-' xin hãy giúp mk với ạ>^<,mk cần rất gấp,mai nộp r ạ,mong mn giúp mk với ạ:(( huhuhu r mk tik cho:<<

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

Tính A= (\(\dfrac{1}{2^2}\)-1) .( \(\dfrac{1}{3^2}\)-1).(\(\dfrac{1}{4^2}\)-1)....(\(\dfrac{1}{100^2}\)-1)

So sánh A= 1+\(\dfrac{1}{2^2}\)+\(\dfrac{1}{3^2}\)+\(\dfrac{1}{4^2}\)+...+\(\dfrac{1}{100^2}\) với 2

Rút gọn biểu thức D= (1-\(\dfrac{1}{2}\) ).(1-\(\dfrac{1}{3}\))....(1-\(\dfrac{1}{2015}\))

Rút gọn biểu thức A= \(\dfrac{3}{4}\).\(\dfrac{8}{9}\).\(\dfrac{15}{16}\).\(\dfrac{24}{25}\)...\(\dfrac{899}{900}\)

tìm x

a, 2 . x \(\frac{-3}{4}\) = \(\frac{-5}{12}\)

b, \(\frac{2}{3}\) + \(\frac{1}{3}\) . x = 7

c, ( 4 . x + \(\frac{1}{8}\) ) = \(\frac{3}{10}\)

d, \(\frac{1}{3}\) . x - 5 = 1\(\frac{1}{2}\)

e, \(\frac{-2}{3}\) . x + \(\frac{1}{3}\) = \(\frac{-1}{2}\)