1/11+2/11+3/11+4/11+...+10/11
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\(\frac{1}{11}+\frac{2}{11}+\frac{3}{11}+\frac{4}{11}+\frac{5}{11}+\frac{6}{11}+\frac{7}{11}+\frac{8}{11}+\frac{9}{11}+\frac{10}{11}\)
\(=\frac{1+2+3+4+5+6+7+8+9+10}{11}\)
\(=\frac{\left(1+10\right)+\left(2+9\right)+\left(3+8\right)+\left(4+7\right)+\left(5+6\right)}{11}\)
\(=\frac{11+11+11+11+11}{11}\)
\(=\frac{11\cdot5}{11}=5\)
\(= \frac{1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10}{11}\)
\(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 = 55\)
Vậy là bằng 55/11 nhé bạn

Dãy này có: (10-1):1+1=10 số hạng
trung bình 1 số là: ( 10/11 +1/11):2=1/2
tổng của dãy là: 1/2*10=5 đ/s:5


=(1/11+10/11)+(2/11+9/11)+(3/11+8/11)+(4/11+7/11)+(5/11+6/11)
=11/11+11/11+11/11+11/11+11/11
=1+1+1+1+1
=5


1/11 + 2/11 + 3/11 + 4/11 + ........... + 10/11
= 1 + 2 + 3 + 4 + ........... + 10
= ( 10 - 1 ) : 1 + 1 = 10
= ( 10 + 1 ) x 10 : 2 = 55
= 55/11 = 5
tk nha. chuc bn hoc gioi

\(\left(-\dfrac{1}{2}\right)^2\div\dfrac{1}{4}-2\times\left(-\dfrac{1}{2}\right)^2\\= \dfrac{1}{4}\div\dfrac{1}{4}-2\times\dfrac{1}{4}\\ =1-\dfrac{1}{2}\\ =\dfrac{1}{2}\)
\(\left(-2\right)^3\times-\dfrac{1}{24}+\left(\dfrac{4}{3}-1\dfrac{5}{6}\right)\div\dfrac{5}{12}\)
= \(-6\times-\dfrac{1}{24}+\left(\dfrac{4}{3}-\dfrac{11}{6}\right)\div\dfrac{5}{12}\)
= \(\dfrac{1}{4}+-\dfrac{1}{2}\div\dfrac{5}{12}\)
= \(\dfrac{1}{4}+-\dfrac{6}{5}\)
= \(\dfrac{1}{4}-\dfrac{6}{5}\)
= \(-\dfrac{19}{20}\)
\(\left(6\dfrac{4}{9}+\dfrac{7}{11}\right)-\left(4\dfrac{4}{9}-2\dfrac{4}{11}\right)\\ =\dfrac{58}{9}+\dfrac{7}{11}-\dfrac{40}{9}+\dfrac{26}{11}\\ =\dfrac{58}{9}-\dfrac{40}{9}+\dfrac{7}{11}+\dfrac{26}{11}\\ =12+3\\ =15\)
\(a,\left(\dfrac{-1}{2}\right)^2:\dfrac{1}{4}-2\left(-\dfrac{1}{2}\right)^2\)
\(=\left(-\dfrac{1}{2}\right)^2\left(4-2\right)\)
\(=\dfrac{1}{4}.2=\dfrac{1}{2}\)
\(b,\left(-2\right)^3.\dfrac{-1}{24}+\left(\dfrac{4}{3}-1\dfrac{5}{6}\right):\dfrac{5}{12}\)
\(=\left(-8\right).\dfrac{-1}{24}+\left(-\dfrac{1}{2}\right).\dfrac{12}{5}\)
\(=\dfrac{1}{3}+\left(-\dfrac{1}{5}\right)=\dfrac{2}{15}\)
\(c,\left(6\dfrac{4}{9}+\dfrac{7}{11}\right)-\left(4\dfrac{4}{9}-2\dfrac{4}{11}\right)\)
\(=\dfrac{701}{99}-\dfrac{206}{99}=\dfrac{495}{99}=5\)
\(d,10\dfrac{1}{5}-5\dfrac{1}{2}.\dfrac{60}{11}+\dfrac{3}{15\%}\)
\(=\dfrac{51}{5}-30+20=\dfrac{1}{5}\)
\(e,\dfrac{5}{7}.\dfrac{5}{11}+\dfrac{5}{7}.\dfrac{2}{11}-\dfrac{5}{7}.\dfrac{14}{11}\)
\(=\dfrac{5}{7}\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)=\dfrac{5}{7}.\left(-\dfrac{7}{11}\right)\)
\(=-\dfrac{5}{11}\)
\(f,\dfrac{-5}{7}.\dfrac{2}{11}+\left(-\dfrac{5}{7}\right).\dfrac{9}{11}+1\dfrac{5}{7}\)
\(=\left(-\dfrac{5}{7}\right)\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+\dfrac{12}{7}\)
\(=\left(-\dfrac{5}{7}\right)+\dfrac{12}{7}=1\)
\(\frac{1}{11}+\frac{2}{11}+\frac{3}{11}+\frac{4}{11}+...+\frac{10}{11}\)
\(=\frac{1+2+3+4+...+10}{11}\)
\(=\frac{\frac{10\times\left(10+1\right)}{2}}{11}\)
\(=\frac{55}{11}=5\)
\(\frac{1}{11}+\frac{2}{11}+\frac{3}{11}+\frac{4}{11}+...+\frac{10}{11}=\frac{1+2+3+4+...+10}{11}=\frac{55}{11}=5\)