\(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right).\left(1-\frac{1}{5}\right)...\left(1-\frac{1}{2016}\right)\)
\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}...\frac{2015}{2016}\)
\(=\frac{1.2.3.4...2015}{2.3.4.5...2016}\)
\(=\frac{1}{2016}\)
Tìm x:\(\left(\frac{1}{3\cdot5}+\frac{1}{5\cdot7}+\frac{1}{7\cdot9}+......+\frac{1}{19\cdot21}\right)\cdot x=\frac{9}{7}\)
HELP ME PLEASE! THANKS A LOT!
a)Tính bằng cách thuận tiện nhất :
\(\frac{1}{2}x\frac{1}{3}+\frac{1}{3}x\frac{1}{4}+\frac{1}{4}x\frac{1}{5}+\frac{1}{5}x\frac{1}{6}\)
b) Tính :
\(\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{4}\right)\)
\(\frac{1}{2}x\frac{1}{3}x\frac{1}{4}x\frac{1}{5}\)
(\(1-\frac{1}{3}\)) x (\(1-\frac{1}{4}\)) x (\(1-\frac{1}{5}\)) x (\(1-\frac{1}{6}\)) x (\(1-\frac{1}{7}\)) x (\(1-\frac{1}{8}\)) \(-\frac{1}{4}\)\(x\frac{1}{2}\)
\(x\)là nhân nhé
lm hộ pls
Tính bằng cáh thuân tiện nhất
1- (\(1-\left(\frac{1}{2}x\frac{3}{5}+\frac{1}{5}x\frac{1}{2}+\frac{2}{10}x\frac{1}{2}+\frac{1}{2}\right)\)
(\(\frac{1}{3}\)+ 1) x (\(\frac{1}{4}\)+ 1) x (\(\frac{1}{5}\)+ 1) x .... x ( \(\frac{1}{16}\)+ 1) = ?
Tính nhanh :
\(\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{4}\right)x....x\left(1-\frac{1}{50}\right)\)
1) Tính A biết rằng :
A = \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+......+\frac{1}{64}\)
2) So sánh 2 phép tính sau:
\(\frac{1+2+3+4+5+6+7}{2+3+4+5+6+7+8}\)và \(\frac{1}{2}+\frac{2}{3}+\frac{3}{4}+\frac{6}{5}+\frac{7}{6}+\frac{8}{7}\)
3) Tìm \(x\)biết:
\(\frac{x\times7}{x}=7\) \(\frac{x}{x\times6}=\frac{1}{6}\)
4) Tìm 1 phân số nếu lấy \(\frac{12}{5}\)trừ đi phân số đó rồi chia cho \(\frac{5}{7}\)thì được \(\frac{12}{5}\).
Đúng ghi Đ, sai ghi S vào chỗ chấm:
a) \(\frac{3}{7}+\frac{1}{3}x\frac{3}{7}=\frac{16}{21}x\frac{3}{7}=\frac{16}{49}\) ......
b)\(\frac{5}{9}+\frac{1}{5}x\frac{5}{6}=\frac{5}{9}x\frac{1}{6}=\frac{13}{18}\) ......
c)\(\frac{13}{9}-\frac{7}{9}:\frac{2}{3}=\frac{6}{9}:\frac{3}{2}=1\) ......
d)\(\frac{11}{8}-\frac{5}{8}:\frac{3}{4}=\frac{11}{8}-\frac{5}{8}x\frac{4}{3}=\frac{11}{8}-\frac{10}{24}=\frac{23}{24}\) ......
