\(A=\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+...+\dfrac{1}{99.100}\\ =\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...+\dfrac{1}{99}-\dfrac{1}{100}\\ =\dfrac{1}{2}-\dfrac{1}{100}=\dfrac{49}{100.}\)
\(A=\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+...+\dfrac{1}{99.100}\\ =\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...+\dfrac{1}{99}-\dfrac{1}{100}\\ =\dfrac{1}{2}-\dfrac{1}{100}=\dfrac{49}{100.}\)
\(\left\{1\dfrac{3}{4}-\dfrac{4}{6}\right\}:\left\{1\dfrac{1}{5}+2\dfrac{2}{5}+\dfrac{1}{5}\right\}< x< 1\dfrac{1}{5}.1\dfrac{3}{4}+3\dfrac{2}{11}:2\dfrac{3}{121}\) với x là số tự nhiên
Tính nhanh
1/2+-1/3+1/4+-1/5+1/6+-1/7+-1/6+1/5+-1/4+1/3+-1/2
-5/7 + 3/4+ -1/5 + -2/7+1/4
a) -3/7+5/13+(-4)/7
b)-5/21+(-2)/21+8/24
c)-1/2+8/10+-2/3+7/9+10/15
d)1/2+(-1)/3+1/4=(-1)/5+1/6+(-1)/7+1/8+1/7+(-1)/6+1/5+1/4+1/3+1/2
(là phân số nhé và dung tính chất phép cộng của phân số) GIÚP MIK NHÉ
CẢM ƠN
Thực hiện phép tính:
\(\left(6-2\dfrac{4}{5}\right).3\dfrac{1}{8}-1\dfrac{3}{5}:\dfrac{1}{4}\)
Cảm ơn ạ!
Tính nhanh :
\(\dfrac{1}{2}+\dfrac{-1}{3}+\dfrac{1}{4}+\dfrac{-1}{5}+\dfrac{1}{6}+\dfrac{-1}{7}+\dfrac{1}{8}+\dfrac{1}{7}+\dfrac{-1}{6}+\dfrac{1}{5}+\dfrac{-1}{4}+\dfrac{1}{3}+\dfrac{-1}{2}\)
\(\dfrac{-29}{12}+1+\dfrac{19}{-12}\)\(\le\)x\(\le\dfrac{-1}{3}+\dfrac{3}{4}+\dfrac{7}{12}\)
\(\dfrac{-5}{3}+1+\dfrac{1}{-3}\le x\le\dfrac{8}{10}+\dfrac{1}{5}+2\)
\(\frac{1}{3}\)+\(\frac{-2}{5}\)+\(\frac{1}{6}\)+\(\frac{-1}{5}\)<x<\(\frac{-3}{4}\)+\(\frac{2}{7}\)+\(\frac{-1}{4}\)+\(\frac{3}{5}\)+\(\frac{5}{7}\)
Trong vở bài tập của bạn An có bài làm sau :
a) \(\dfrac{-3}{5}+\dfrac{1}{5}=\dfrac{4}{5}\)
b) \(\dfrac{-10}{13}+\dfrac{-2}{16}=\dfrac{-12}{13}\)
c) \(\dfrac{2}{3}+\dfrac{-1}{6}=\dfrac{4}{6}+\dfrac{-1}{6}=\dfrac{3}{2}=\dfrac{1}{2}\)
d) \(\dfrac{-2}{3}+\dfrac{2}{-5}=\dfrac{-2}{3}+\dfrac{-2}{5}=\dfrac{-10}{15}+-\dfrac{6}{15}=\dfrac{-4}{15}\)
Hãy kiểm tra lại các đáp số và sửa lại chỗ sai (nếu có)