Thực hiện phép tính: \(1-\frac{3}{2\times10}-\frac{3}{4\times15}-\frac{3}{6\times20}-\frac{3}{8\times25}-...-\frac{3}{198\times500}\)
C=\(1-\frac{3}{2\times10}-\frac{3}{4\times15}-\frac{3}{6\times20}-\frac{3}{8\times25}-...-\frac{3}{1340\times3355}\)
Tính nhanh:\(\frac{1\times2\times3+2\times4\times6+3\times6\times9+4\times8\times12+5\times10\times15}{1\times3\times5+2\times6\times10+3\times9\times15+4\times12\times20+5\times15\times25}-\frac{1+2+3+2+4+6+3+6+9+4+8+12+5+10+15}{1+3+5+2+6+10+3+9+15+4+12+20+5+15+25}\)
Tính nhanh : \(\frac{1}{8}\div12,5\%+\left(\frac{1\times2\times3+6\times4\times2}{5\times3\times1+5\times15\times25}+\frac{1}{2}\div50\%\right)-\left(\frac{1}{16}\div6,25\%+\frac{3+2+1+2+4+6}{1+3+5+25+15+5}\right)-\frac{1}{4}\div25\%\)
\(\frac{1}{8}=12,5\%\) ; \(\frac{1}{16}=6,25\%\) ; \(\frac{1}{2}=50\%\) ; \(\frac{1}{4}=25\%\)
Thay vào trên mà tính.
= \(1+\left(\frac{3\left(1x2+2x4x2\right)}{3\left(5+5x3x25\right)}+1\right)-\left(1+\frac{18}{54}\right)-1\) = \(\frac{18}{380}-\frac{18}{54}\)
\(\frac{3}{8\times11}+\frac{4}{11\times15}+\frac{5}{15\times20}+\frac{6}{20\times26}+\frac{7}{26\times33}+\frac{8}{33\times41}+\frac{9}{41\times50}=\frac{2}{5}-2\times x\)
làm ơn giúp em giải bài toán này!!!!!!!!
\(T\text{Í}NH:a,\frac{3}{8\times11}+\frac{3}{11\times14}+\frac{3}{14\times17}+\frac{3}{17\times10}\)
\(b,\frac{6}{13\times19}+\frac{6}{19\times25}+...+\frac{6}{613\times619}\)
A = 3 / 8 x 11 + 3 / 11 x 14 + 3 / 14 x 17 + 3 / 17 x 10
A = 1 / 8 - 1 / 11 + 1 / 11 - 1 / 14 + 1 / 14 - 1 / 17 + 1 / 17 - 1 / 10
A = 1 / 8 - 1 / 10
A = 1 / 40
B = 6 / 13 x 19 + 6 / 19 x 25 + ... + 6 / 613 x 619
B = 1 / 13 - 1 / 19 + 1 / 19 - 1 / 25 + ... + 1 / 613 - 1 / 619
B = 1 / 13 - 1 / 619
B = 606 / 8047
k mk nha
phần a phân số cuối có mẫu sai hay sao ý
A = 3 / 8 x 11 + 3 / 11 x 14 + 3 / 14 x 17 + 3 / 17 x 10
A = 1 / 8 - 1 / 11 + 1 / 11 - 1 / 14 + 1 / 14 - 1 / 17 + 1 / 17 - 1 / 10
A = 1 / 8 - 1 / 10
A = 1 / 40
B = 6 / 13 x 19 + 6 / 19 x 25 + ... + 6 / 613 x 619
B = 1 / 13 - 1 / 19 + 1 / 19 - 1 / 25 + ... + 1 / 613 - 1 / 619
B = 1 / 13 - 1 / 619
B = 606 / 8047
N = \(\frac{1}{1\times5}+\frac{1}{5\times10}+\frac{1}{10\times15}+\frac{1}{15\times20}+...+\frac{1}{2005\times2010}\)
Tìm số N.
Nhankk nkaa minkk t i c k , à maa minkk ckỉ tickk ckoo 5 bạn có câu trả lời đầy đủ và nhank nkất nkaa <3
*Mình không chép đề bài nka
\(N=\frac{4}{1.5}\)\(+\frac{4}{5.10}\)\(+\frac{4}{10.15}\)\(+\frac{4}{15.20}\)\(+...+\frac{4}{2005.2010}\)
\(N=1-\frac{1}{5}\)\(+\frac{1}{5}\)\(-\frac{1}{10}\)\(+\frac{1}{10}\)\(-\frac{1}{15}\)\(+\frac{1}{15}\)\(-\frac{1}{20}\)\(+...+\frac{1}{2005}\)\(-\frac{1}{2010}\)
\(N=1-\frac{1}{2010}\)
\(N=\frac{2009}{2010}\)
#Tường Vy ( Ninh Nguyễn )
N = \(\frac{1}{1}-\frac{1}{5}+\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}\)\(+\frac{1}{15}-\frac{1}{20}+.....+\frac{1}{2005}-\frac{1}{2010}\)
N = 1 - \(\frac{1}{2010}\)
N = \(\frac{2009}{2010}\)
\(N=\frac{1}{1\times5}+\frac{1}{5\times10}+\frac{1}{10\times15}+.....+\frac{1}{2005\times2010}.\)
\(N=\frac{1}{1\times5}+\frac{1}{5}\left(\frac{1}{1\times5}+\frac{1}{5\times10}+\frac{1}{10\times15}+.....+\frac{1}{2005\times2010}\right)\)
\(N=\frac{1}{1\times5}+\frac{1}{5}\left(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+......+\frac{1}{2005}+\frac{1}{2010}\right)\)
\(N=\frac{1}{1\times5}+\frac{1}{5}\left(1-\frac{1}{2010}\right)\)
\(N=\frac{1}{1\times5}+\frac{1}{5}\left(\frac{2009}{2010}\right)\)
\(N=\frac{1}{1\times5}+\frac{2009}{10050}\)
\(N=\frac{4019}{10050}\)
Bài 4: Tính nhanh:
a, A =\(\left(\frac{84}{13}\right)^2+\left(\frac{35}{13}\right)^2\)
b, B = \(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}\div\frac{3+\frac{3}{13}+\frac{3}{169}+\frac{3}{91}}{7+\frac{7}{13}+\frac{7}{169}+\frac{7}{91}}\)
c, C =\(\frac{1\times2+2\times4+3\times6+4\times8+5\times10}{3\times4+6\times8+9\times12+12\times16+15\times20}\)
thực hiện phép tính \(\frac{\frac{3}{7}-\frac{3}{11}+\frac{3}{13}}{\frac{5}{7}-\frac{5}{11}+\frac{5}{13}}+\frac{\frac{1}{2}-\frac{1}{3}+\frac{1}{4}}{\frac{5}{4}-\frac{5}{6}+\frac{5}{8}}\)
Thực hiện phép tính:
M=\(\frac{-3}{4}.\frac{2}{11}+\frac{-3}{4}.\frac{9}{11}+2\frac{3}{4}\)
N= \(\frac{6}{8}+\frac{5}{8}:5-\frac{3}{16}\left(-4\right)^2\)
\(M=\frac{-3}{4}.\frac{2}{11}+\frac{-3}{4}.\frac{9}{11}+2\frac{3}{4}\)
\(M=\frac{-3}{22}+\frac{-27}{44}+\frac{2\times4+3}{4}\)
\(M=\frac{-3}{22}+\frac{-27}{44}+\frac{11}{4}\)
\(M=\frac{-6}{44}+\frac{-27}{44}+\frac{121}{44}\)
\(M=\frac{-33}{44}+\frac{121}{44}\)
\(M=2\)