M = \(54-\frac{1}{2}\left(1+2\right)-\frac{1}{3}\left(1+2+3\right)-...-\frac{1}{12}\left(1+2+3+...+12\right)\)
\(54-\left(\frac{3}{2}+\frac{4}{2}+...+\frac{13}{2}\right)=54-\frac{1}{2}\left(3+4+5+...+13\right)=54-\frac{1}{2}.176=54-88\)
= -24
M = \(54-\frac{1}{2}\left(1+2\right)-\frac{1}{3}\left(1+2+3\right)-...-\frac{1}{12}\left(1+2+3+...+12\right)\)
\(54-\left(\frac{3}{2}+\frac{4}{2}+...+\frac{13}{2}\right)=54-\frac{1}{2}\left(3+4+5+...+13\right)=54-\frac{1}{2}.176=54-88\)
= -24
Tính:
A=\(\left(1-\frac{2}{3}+\frac{4}{3}\right)-\left(\frac{4}{5}-1\right)+\left(\frac{7}{5}+2\right)\)
B=\(\left(-3+\frac{3}{4}-\frac{1}{3}\right):\left(5+\frac{2}{5}-\frac{2}{3}\right)\)
C=\(\left(\frac{3}{5}-\frac{4}{15}\right).\left(\frac{2}{7}-\frac{3}{14}\right)-\left(\frac{5}{9}-\frac{7}{27}\right)\)\(.\left(1-\frac{3}{5}\right)+\left(1-\frac{11}{12}\right).\left(1+\frac{11}{12}\right)\)
D=\(\frac{\left(\frac{3}{10}-\frac{4}{15}-\frac{7}{20}\right).\frac{-5}{19}}{\left(\frac{1}{14}+\frac{1}{7}-\frac{-3}{35}\right).\frac{4}{3}}\)
12)\(0,2.\frac{15}{36}-\left(\frac{2}{5}+\frac{2}{3}\right):1\frac{1}{5}\)
13)\(1\frac{13}{15}.0,75-\left(\frac{8}{15}+0,25\right).\frac{24}{27}\)
16)\(\frac{1}{2}+\frac{3}{4}-\left(\frac{3}{4}-\frac{4}{5}\right).\left(-2,75\right)\)
18)\(\left(\frac{7}{8}-\frac{3}{4}\right).1\frac{1}{3}-\frac{2}{7}.\left(3.5\right)^2\)
22)\(1\frac{13}{15}.0,75-\left(\frac{11}{20}+25\%\right):\frac{7}{3}\)
23)\(\frac{\left(\frac{2}{3}-0,75\right).\left(0,2-\frac{2}{5}\right)}{\frac{5}{9}-1\frac{1}{12}}\)
33)\(\left(25\%+\frac{1}{3}+0,75\right):\left(4\frac{3}{4}-3\frac{1}{2}\right)\)
35)\(\left(\frac{377}{-231}-\frac{123}{89}+\frac{34}{791}\right).\left(\frac{1}{6}-\frac{1}{8}-\frac{1}{24}\right)\)
a\(\left[6+\left(\frac{1}{2}\right)^3-\left|-\frac{1}{2}\right|\right]:\frac{3}{12}\)
b\(\frac{4}{9}.19\frac{1}{3}-\frac{4}{9}.39\frac{1}{3}\)
c\(\left(-\frac{1}{2}\right)^2:\frac{1}{4}-2\left(-\frac{1}{2}\right)\)
Tính giá trị của các biểu thức sau
1)\(\left(3\frac{5}{12}-1\frac{8}{9}\right):\left(0,25-2\frac{1}{12}\right)\)
2)\(\left(1\frac{4}{7}-2\frac{2}{5}\right):\left(1\frac{1}{8}-4\frac{3}{4}\right)\)
1) \(\frac{2}{5}x\frac{1}{3}-\frac{2}{15}:\frac{1}{5}+\frac{3}{5}x\frac{1}{3}\)
2)\(\left(3\frac{1}{3}+2,5\right):\left(3\frac{1}{6}-4\frac{1}{5}\right)-\frac{11}{31}\)
3)\(\left[6+\left(\frac{1}{2}\right)^3-\left|-\frac{1}{2}\right|\right]:\frac{3}{12}\)
4)\(\frac{18}{37}+\frac{8}{24}+\frac{19}{37}-1\frac{23}{24}+\frac{2}{3}\)
5)\(\left(-2\right)^3x\left(\frac{3}{4}-0,25\right):\left(2\frac{1}{4}-1\frac{1}{6}\right)\)
6)\(\left(\frac{2}{5}\right)^2+5\frac{1}{2}x\left(45-2\right)+\frac{23}{4}\)
7)\(\frac{4}{9}-19\frac{1}{3}-\frac{4}{9}x39\frac{1}{3}\)
8)\(\left(-\frac{1}{2}\right)^2:\frac{1}{4}-2x\left(-\frac{1}{2}\right)^2\)
9)\(125\%x\left(-\frac{1}{2}\right)^3:\left(1\frac{5}{16}-1,5\right)+2008^0\)
giúp mình nha mai mình học rùi
\(\left(\frac{3}{8}+\frac{-3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
\(\frac{1}{2}+\frac{3}{4}-\left(\frac{3}{4}-\frac{4}{5}\right)\)
\(6\frac{5}{12}:2\frac{3}{4}+11\frac{1}{4}\left(\frac{1}{3}-\frac{1}{5}\right)\)
\(\left(\frac{7}{8}-\frac{3}{4}\right)1\frac{1}{3}-\frac{2}{7}\left(3,5\right)^2\)
\(\left(\frac{3}{5}+0,415-\frac{3}{200}\right)2\frac{2}{3}.0,25\)
Thực hiện các phép tính
cảm ơn
Tìm x
\(\frac{5}{2}-\left(\frac{3}{2}-2\frac{1}{3}+x\right)=\frac{8}{15}-\left(\frac{1}{4}-\frac{7}{10}\right)\)
\(1\frac{2}{3}-1\frac{3}{5}+x=\frac{2}{5}-\left|\frac{3}{4}-\frac{7}{8}\right|\)
\(2-\left(\frac{2}{3}-3\frac{1}{4}+x\right)=1\left|\frac{1}{6}-\frac{13}{12}\right|\)
Câu 1: Tính
a) A=\(\left(\frac{1}{2^2}-1\right).\left(\frac{1}{3^2}-1\right).....\left(\frac{1}{98^2}-1\right).\left(\frac{1}{99^2}-1\right)\)
b) B=\(\frac{1}{2}:\left(-1\frac{1}{2}\right):1\frac{1}{3}:\left(-1\frac{1}{4}\right):1\frac{1}{5}:\left(-1\frac{1}{6}\right):...:\left(-1\frac{1}{100}\right)\)
c) C=\(\frac{4^6.9^5+6^9.120}{-8^4.3^{12}+6^4}\)
1/ Tính tổng:
M =\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}\)
2/Tìm X:
\(\frac{1}{21}+\frac{1}{28} +\frac{1}{36} +.....+\frac{2}{x.\left(x+1\right)}=\frac{2}{9}\)
3/Tính tích sau rồi tìm số nghịch đảo của kết quả:
\(T=\left(1-\frac{1}{3}\right)\left(1-\frac{1}{5}\right)\left(1-\frac{1}{7}\right)\left(1-\frac{1}{9}\right)\left(1-\frac{1}{11}\right)\left(1-\frac{1}{2}\right)\left(1-\frac{1}{4}\right)\left(1-\frac{1}{6}\right)\left(1-\frac{1}{8}\right)\left(1-\frac{1}{10}\right)\)
4/ TÍnh giá trị của biểu thức:
\(\frac{1^2}{1.2}.\frac{2^2}{2.3}.\frac{3^2}{3.4}\frac{4^2}{4.5}\)