`#3107.101107`
`35 1/6 \div (-4/5) - 45 1/6 \div -4/5`
`= 35 1/6 * (-5/4) - 45 1/6 *(-5/4)`
`= -5/4*(35 1/6 - 45 1/6)`
`= -5/4 * (35 + 1/6 - 45 - 1/6)`
`= -5/4 * (-10)`
`= 12,5`
tính nhanh :
\(\dfrac{-1}{6}+\dfrac{5}{-12}+\dfrac{7}{12}\)
\(\dfrac{4}{45}+\dfrac{-1}{45}+\dfrac{7}{45}+\dfrac{4}{45}+\dfrac{-2}{45}+\dfrac{-1}{5}\)
Bài 1.( 2 điểm)Tính bằng cách hợp lí:
a) \(\dfrac{1}{2}+\dfrac{9}{10}+\dfrac{5}{6}-\dfrac{11}{14}-\dfrac{1}{3}+\dfrac{-4}{35}\)
b) \(\left(\dfrac{18}{23}+\dfrac{7}{12}\right)+\left(\dfrac{-13}{19}-\dfrac{3}{4}\right)+\left(\dfrac{-6}{19}+\dfrac{5}{23}\right)\)
c) \(\dfrac{4}{3}+\dfrac{-5}{6}+\dfrac{-1}{4}\)
d) \(\dfrac{5}{6}-\dfrac{7}{5}+\dfrac{17}{30}\)
Tính hợp lý:
\(a.\dfrac{3}{17}+\dfrac{-5}{13}+\dfrac{-18}{35}+\dfrac{14}{17}+\dfrac{17}{-35}+\dfrac{-8}{13}\)
\(b.\dfrac{-3}{8}\cdot\dfrac{1}{6}+\dfrac{3}{-8}\cdot\dfrac{5}{6}+\dfrac{-10}{16}\)
\(c.\dfrac{-4}{11}\cdot\dfrac{5}{15}\cdot\dfrac{11}{-4}\)
Bài 1. Tính
A= \(\left(8\dfrac{2}{7}-4\dfrac{2}{7}\right)-3\dfrac{4}{9}\)
B= \(\left(10\dfrac{2}{9}-6\dfrac{2}{9}\right)+2\dfrac{3}{5}\)
Bài 2. Tính
a) \(5\dfrac{1}{2}.3\dfrac{1}{4}\) b) \(6\dfrac{1}{3}:4\dfrac{2}{9}\) c) \(4\dfrac{3}{7}.2\)
A=\(\dfrac{2}{3}\)+\(\dfrac{14}{15}\)+\(\dfrac{34}{35}\)+\(\dfrac{62}{63}\)+\(\dfrac{98}{99}\)+\(\dfrac{142}{143}\)+\(\dfrac{194}{195}\)
Và B=5+\(\dfrac{1}{2^2}\)+\(\dfrac{1}{3^3}\)+\(^{\dfrac{1}{4^4}}\)+\(\dfrac{1}{5^5}\)+\(\dfrac{1}{6^6}\)+\(\dfrac{1}{7^7}\).So sánh A và B
tính một cách hợp lí:
a) \(\dfrac{-5}{18}+\dfrac{32}{45}-\dfrac{9}{10}\)
b) \(\left(\dfrac{-1}{4}+\dfrac{51}{33}-\dfrac{5}{3}\right)-\left(\dfrac{-15}{12}+\dfrac{6}{11}-\dfrac{42}{29}\right)\)
c) \(1-\dfrac{1}{2}+2-\dfrac{2}{3}+3-\dfrac{3}{4}+4-\dfrac{1}{4}-3-\dfrac{1}{3}-2-\dfrac{1}{2}-1\)
giải chi tiết giúp mình nha
a, Tính: M = \(1+\dfrac{1}{5}+\dfrac{3}{35}+...+\dfrac{3}{9603}+\dfrac{3}{9999}\)
b, Chứng tỏ: S = \(\dfrac{1}{4^2}+\dfrac{1}{6^2}+\dfrac{1}{8^2}+...+\dfrac{1}{\left(2n\right)^2}< \dfrac{1}{4}\left(n\in N,n\ge2\right)\)
1, 12:(\(\dfrac{3}{4}\)-\(\dfrac{5}{6}\))2
2,\(\dfrac{7}{23}\).[(-\(\dfrac{8}{6}\))-\(\dfrac{45}{18}\)]
tìm x biết
a)x-\(\dfrac{3}{7}\)=\(\dfrac{2}{5}.\dfrac{1}{4}\)
b)x+\(\dfrac{4}{5}\)=\(\dfrac{-5}{12}\).\(\dfrac{3}{25}\)
c)\(\dfrac{x}{182}\)=\(\dfrac{-6}{12}\).\(\dfrac{35}{91}\)
Tính:
\(a,\left(\dfrac{5}{12}-\dfrac{3}{4}\right).\dfrac{-6}{5}+\dfrac{-7}{6}\)
\(b,\left(5\dfrac{1}{2}-5\right)^2+\dfrac{-1}{6}:\dfrac{5}{3}\)
\(c,75\%-1\dfrac{1}{2}+0,5:\dfrac{5}{12}\)
