Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
=2/10+3/10+4/10+......+13/10
=\(\frac{2+3+4+......+13}{10}\)
=90/10=9
k cho mình nha
mình biết đáp án là : \(\frac{9}{16}\)thôi,còn cách giải thì mình không chắc chắn nên không viết ra
\(\frac{3.2.4.3.5.4.6.5.7.6.8.7.9}{4.3.3.4.4.5.5.6.6.7.7.8.8}\)= \(\frac{9}{16}\)
\(\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.\frac{24}{25}...\frac{63}{64}\)
\(=\frac{1.3}{2.2}.\frac{2.4}{3.3}.\frac{3.5}{4.4}.\frac{4.6}{5.5}...\frac{7.9}{8.8}\)
\(=\frac{1.3.2.4.3.5.4.6...7.9}{2.2.3.3.4.4.5.5...8.8}\)
\(=\frac{1.9}{2.8}=\frac{9}{16}\)
\(A=\frac{8}{9}.\ \frac{15}{16}.\ \frac{24}{25}.\ \frac{35}{36}.\ \frac{48}{49}.\ \frac{63}{64}\)
\(A=\frac{2.4}{3^2}.\ \frac{3.5}{4^2}.\ \frac{4.6}{5^2}.\ \frac{5.7}{6^2}.\ \frac{6.8}{7^2}.\ \frac{7.9}{8^2}\)
\(A=\frac{2.3.4^2.5^2.6^2.7^2.8.9}{3^2.4^2.5^2.6^2.7^2.8^2}\)
\(A=\frac{2.9}{3.8}\)
\(A=\frac{3}{4}\)
Ta có:
\(\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.\frac{24}{25}.\frac{35}{36}.\frac{48}{49}=\frac{1.3}{2.2}+\frac{2.4}{3.3}+\frac{3.5}{4.4}+\frac{4.6}{5.5}+\frac{5.7}{6.6}+\frac{6.8}{7.7}=\frac{1.2.3.4.5.6}{2.3.4.5.6.7}.\frac{3.4.5.6.7.8}{2.3.4.5.6.7}=\frac{1}{7}.\frac{8}{2}=\frac{4}{7}\)
\(a,\frac{3}{27}+\frac{1}{4}-\frac{1}{9}=\frac{3}{27}+\frac{1}{4}-\frac{3}{27}=\frac{3}{27}-\frac{3}{27}+\frac{1}{4}=\frac{1}{4}\)
\(b,\frac{72}{25}\cdot\frac{75}{36}=\frac{72\cdot75}{25\cdot36}=\frac{2\cdot36\cdot25\cdot3}{25\cdot36}=\frac{2\cdot3}{1\cdot1}=6\)
\(c,\frac{36}{49}:\frac{48}{14}=\frac{36}{49}\cdot\frac{14}{48}=\frac{36\cdot14}{49\cdot48}=\frac{3\cdot12\cdot2\cdot7}{7\cdot7\cdot4\cdot12}=\frac{3\cdot2}{7\cdot4}=\frac{6}{28}=\frac{3}{14}\)
\(d,\frac{39}{23}:26=\frac{39}{23}\cdot\frac{1}{26}=\frac{39}{23\cdot26}=\frac{3\cdot13}{23\cdot2\cdot13}=\frac{3}{23\cdot2}=\frac{3}{46}\)
\(e,45:\frac{15}{2}=\frac{45}{1}\cdot\frac{2}{15}=\frac{45\cdot2}{15}=\frac{3\cdot15\cdot2}{15}=\frac{6}{1}=6\)
\(g,\frac{57}{8}:\frac{3}{4}-\frac{15}{7}\cdot\frac{14}{25}=\frac{57\cdot4}{8\cdot3}-\frac{15\cdot14}{7\cdot25}=\frac{3\cdot19\cdot4}{2\cdot4\cdot3}-\frac{3\cdot5\cdot2\cdot7}{7\cdot5\cdot5}\)
\(=\frac{19}{2}-\frac{3\cdot2}{5}=\frac{95}{10}-\frac{12}{10}=\frac{83}{10}\)
#)Giải :
\(\frac{1}{15}+\frac{4}{30}+\frac{9}{45}+\frac{16}{60}+...+\frac{81}{135}=\frac{1}{15}+\frac{2}{15}+\frac{3}{15}+...+\frac{9}{15}=\frac{45}{15}=3\)
Dễ ẹc ak :v rút gọn là ra
=(\(\frac{1}{15}\)+\(\frac{4}{30}\)+\(\frac{16}{60}\)+\(\frac{64}{120}\))+(\(\frac{9}{45}\)+\(\frac{36}{90}\))+(\(\frac{25}{75}\)+\(\frac{81}{135}\))
=(\(\frac{8}{120}\)+\(\frac{16}{120}\)+\(\frac{32}{120}\)+\(\frac{64}{120}\))+(\(\frac{18}{90}\)+\(\frac{36}{90}\))+\(\frac{14}{15}\).
=1+\(\frac{3}{5}\)+\(\frac{14}{15}\).
=\(\frac{8}{5}\)+\(\frac{14}{15}\).
=\(\frac{15}{38}\)