\(\dfrac{15}{28}-\dfrac{186}{1116}-\dfrac{121}{462}+\dfrac{198}{189}\)
\(=\dfrac{31}{84}-\dfrac{121}{462}+\dfrac{198}{189}\)
\(=\dfrac{3}{28}+\dfrac{198}{189}\)
\(=\dfrac{97}{84}\)
tính theo cách hợp lý
a)\(\dfrac{4}{20}+\dfrac{16}{42}+\dfrac{6}{15}+\dfrac{-3}{5}+\dfrac{2}{21}+\dfrac{-40}{21}+\dfrac{3}{20}\)
B)\(\dfrac{42}{46}+\dfrac{250}{186}+\dfrac{-2121}{2323}+\dfrac{-125125}{143143}\)
Tính nhanh
\(\dfrac{1^2}{1.2}.\dfrac{2^2}{2.3}.\dfrac{3^2}{3.4}....\dfrac{99^2}{99.100}\)
\(\left(\dfrac{2}{175}-\dfrac{7}{25}+\dfrac{3}{5}\right).\left(\dfrac{4}{11}+\dfrac{3}{121}-\dfrac{47}{121}\right)\)
\(\dfrac{-2}{5}\left(\dfrac{5}{17}-\dfrac{9}{15}\right)-\dfrac{2}{5}\left(\dfrac{2}{17}+\dfrac{-2}{5}\right)\)
Phiền giúp gấp được không ạ? Tối nay nữa thôi :(((
\(\dfrac{1}{6}+\dfrac{1}{10}+\dfrac{1}{15}+\dfrac{1}{21}+\dfrac{1}{28}+\dfrac{1}{36}+\dfrac{1}{45}\)
ai nhanh mk like cho
Tính nhanh:
a) \(A=\dfrac{5}{1\cdot5}=\dfrac{5}{5\cdot10}+\dfrac{5}{10\cdot15}+...+\dfrac{5}{9995\cdot10000}\)
b) \(B=\dfrac{1}{420}+\dfrac{1}{462}+\dfrac{1}{506}+...+\dfrac{1}{1560}\)
Tính tổng
A= \(\dfrac{1}{15}+\dfrac{1}{21}+\dfrac{1}{28}+...+\dfrac{1}{105}\)
1.Tính giá trị biểu thức : \(\dfrac{5.2010-1996}{14+4.2010}\).\(\dfrac{15+\dfrac{15}{7}-\dfrac{15}{11}+\dfrac{15}{2009}-\dfrac{15}{13}}{\dfrac{4}{2009}-\dfrac{4}{13}+\dfrac{4}{7}-\dfrac{4}{11}+4}\)
2. Tìm tất cả SNT p sao cho p + 2 và p + 28 là SNT
3. Cho A = 1 - 3 + 32 - 33 + ... - 32009 + 32010 . Chứng minh 4A - 1 là một luỹ thừa của 3.
Phép tính lằng nhằng ***** nhỉ ?????
Help Me vs ! Bn nào nhanh nhất , đúng nhất mik tặng tik !*(Lời giải chi tiết )* nội trong đêm nay nhé !
Tính :
A=\(\dfrac{1}{10}+\dfrac{1}{15}+\dfrac{1}{21}+......+\dfrac{1}{120}\)
B=\(\dfrac{4}{3.7}+\dfrac{4}{7.11}+\dfrac{4}{11.15}+......+\dfrac{4}{107.111}\)
C=\(\dfrac{7}{10.11}+\dfrac{7}{11.12}+\dfrac{7}{12.13}+......+\dfrac{7}{69.70}\)
D=\(\dfrac{15}{90.94}+\dfrac{15}{94.98}+\dfrac{15}{98.102}+......+\dfrac{15}{146.150}\)
Chứng minh rằng:
\(\dfrac{1}{5}-\dfrac{1}{14}+\dfrac{1}{28}+\dfrac{1}{44}+\dfrac{1}{61}+\dfrac{1}{85}+\dfrac{1}{97}< \dfrac{1}{2}\)
Tính
A=\(\left(\dfrac{1}{3}-1\right)\left(\dfrac{1}{6}-1\right)\left(\dfrac{1}{10}-1\right)\left(\dfrac{1}{15}-1\right)\left(\dfrac{1}{21}-1\right)\left(\dfrac{1}{28}-1\right)\left(\dfrac{1}{36}-1\right)\)
B=\(\left(1-\dfrac{1}{2^2}\right)\left(1-\dfrac{1}{3^2}\right)........\left(1-\dfrac{1}{10^2}\right)\)
C=\(1+\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+..........+\dfrac{1}{2^{2016}}\)
Giúp mk nha!Cảm ơn rất nhìu!
