Tinh gia tri cua bieu thuc \(D=\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{200}\)

Nho giai va tring bay cach lam cho minh luon nha ^_^

bai 1 :thuc hien phep tinh

a)\(\frac{-5}{2}:\left(\frac{3}{4}-\frac{1}{2}\right)\)      b)  \(11\frac{3}{13}-\left(2\frac{4}{7}+5\frac{3}{13}\right)\)     c)\(\left(\frac{-5}{24}+0,75+\frac{7}{12}\right):\left(-2\frac{1}{4}\right)^2\)

AI LAM NHANH VA DUNG THI MK SE TICK CHO NHA

MK DAG CAN GAP !!!!!!! CAC BAN LAM NHANH LEN NHA

Tinh gia tri cua bieu thuc \(D=\frac{1}{6}+\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+\frac{1}{45}\)

Nho giai va trinh bay cach lam cho minh luon nha ^_^

tinh gia try bieu thuc 

A=\(\left[\frac{1}{7}+\frac{1}{23}-\frac{1}{1009}\right]:\left[\frac{1}{23}+\frac{1}{7}-\frac{1}{1009}+\frac{1}{7}\times\frac{1}{23}\times\frac{1}{1009}\right]+1:\left[30\times1009-160\right]\)

ai lam dung co ca cach lam cho 1 like

bài 1 cho a,b,c là 3 độ dài 3 cạnh tam giác

CMR \(\frac{1}{a+b-c}+\frac{1}{b+c-a}+\frac{1}{a+c-b}>=\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\)

co ai biet lam k lam giup minh di. minh dang can lam. cac ban than dong tren OLM giup minh di

\(Cho\:A=\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}\)

a) Chứng minh A lớn hơn hoặc bằng \(\frac{4}{3}\)

b) Chứng minh A bé hơn hoặc bằng 2,5

Cho A=\(\frac{1}{11}+\frac{1}{12}+...+\frac{1}{70}CMR:\frac{4}{3}< A< \frac{5}{2}\)

Cho A=\(\frac{1}{11}+\frac{1}{12}+\frac{1}{13}+...+\frac{1}{70}.Chungminhrang\frac{4}{3}< A< \frac{5}{2}\)