\(\dfrac{\dfrac{2}{45}-\dfrac{4}{13}-\dfrac{1}{3}}{\dfrac{3}{13}-\dfrac{4}{15}+\dfrac{2}{3}}=\left(\dfrac{4}{13}-\dfrac{3}{13}\right):\left(\dfrac{2}{45}-\dfrac{4}{15}\right):\left(\dfrac{1}{3}-\dfrac{2}{3}\right)\\=\dfrac{1}{13}:\dfrac{-10}{45}:\dfrac{-1}{3}=\dfrac{1}{13}.\dfrac{-45}{10}.\left(-3\right)=\dfrac{135}{130}=\dfrac{27}{26}\)
\(\text{Thực hiện phép tính một cách hợp lý nhất (nếu có thể):}\)
\(1\)) \(\left(\dfrac{-8}{13}:\dfrac{3}{7}+\dfrac{-5}{13}:\dfrac{3}{7}\right).\dfrac{\left(-4\right)^3.\left|-3\right|}{7}\)
\(2\)) \(75\)\(\text{%}\)\(-\left(\dfrac{5}{2}+\dfrac{5}{3}\right)+\left(-\dfrac{1}{2}\right)^2\)
Chứng minh rằng P>3 biet P= \(\dfrac{5}{2×1}+\dfrac{4}{1×11}+\dfrac{3}{11×2}+\dfrac{1}{2×15}+\dfrac{13}{15×4}+\dfrac{15}{4×43}+\dfrac{13}{43×8}\)
Tính hợp lý :
a,\(\left(\dfrac{136}{15}-\dfrac{28}{5}+\dfrac{62}{10}\right).\dfrac{21}{24}\)
b,\(\dfrac{3}{11}.\dfrac{4}{11}+\left(\dfrac{3}{13}.\dfrac{4}{11}-\dfrac{1}{13}\right)\)
\(\dfrac{\dfrac{3}{7}-\dfrac{3}{11}+\dfrac{3}{13}}{\dfrac{5}{7}-\dfrac{5}{11}+\dfrac{5}{13}}+\dfrac{\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{4}}{\dfrac{5}{4}-\dfrac{5}{6}+\dfrac{5}{8}}\)
THỰC HIỆN PHÉP TÍNH NHA MN
\(\left(\dfrac{2}{3}+\dfrac{2}{13}+\dfrac{2}{11}+\dfrac{2}{6}\right)\) \(\left(\dfrac{5}{4}+\dfrac{5}{7}+\dfrac{5}{6}+\dfrac{5}{11}\right)\)
___________________ X ___________________
\(\left(\dfrac{4}{3}+\dfrac{4}{13}+\dfrac{4}{11}+\dfrac{4}{6}\right)\) \(\left(\dfrac{9}{4}+\dfrac{9}{7}+\dfrac{9}{6}\dfrac{9}{11}\right)\)
Tính :
a, \(\dfrac{3\cdot13-13\cdot18}{15\cdot40-80}\);
b, \(\dfrac{18\cdot34+\left(-18\right)\cdot124}{-36\cdot17+9\cdot\left(-52\right)}\);
c, \(\dfrac{\dfrac{3}{41}-\dfrac{12}{47}+\dfrac{27}{53}}{\dfrac{4}{41}-\dfrac{16}{47}+\dfrac{36}{53}}+\dfrac{-0,25\cdot\dfrac{-2}{3}-0,75:\left(\dfrac{-1}{2}+\dfrac{2}{3}\right)}{\left|-1\dfrac{1}{2}\right|\cdot\left(\dfrac{-2}{3}-75\%:\dfrac{3}{-2}\right)}\).
1. thực hiện phép tính
a. \(\dfrac{11}{21}\)+\(\dfrac{-4}{7}\)
b. \(\dfrac{5}{15}\)+\(\dfrac{14}{25}\)-\(\dfrac{12}{9}\)+\(\dfrac{2}{7}\)+\(\dfrac{11}{25}\)
c. \(\dfrac{2}{3}\)+\(\dfrac{5}{7}\)-\(\dfrac{3}{14}\)
d. \(\dfrac{2}{5}\)-\(\dfrac{3}{7}\)+\(\dfrac{9}{45}\)
e.\(\dfrac{21}{47}\)+\(\dfrac{9}{45}\)+\(\dfrac{26}{47}\)+\(\dfrac{45}{5}\)
f. \(\dfrac{15}{12}\)-\(\dfrac{18}{13}\)+\(\dfrac{5}{13}\)-\(\dfrac{3}{12}\)
g. \(\dfrac{-8}{18}\)-\(\dfrac{15}{27}\)
h.\(\dfrac{3}{7}\)+\(\dfrac{-5}{2}\)-\(\dfrac{3}{5}\)
i.(\(\dfrac{11}{12}\):\(\dfrac{33}{16}\)).\(\dfrac{3}{5}\)
a) \(\left(7\dfrac{4}{9}+3\dfrac{7}{11}\right)-3\dfrac{4}{9}\)
b) \(5\dfrac{2}{7}\cdot\dfrac{8}{11}+5\dfrac{2}{7}\cdot\dfrac{5}{11}-5\dfrac{2}{7}\cdot\dfrac{2}{11}\)
c) \(1\dfrac{13}{15}\cdot0,75-\left(\dfrac{11}{20}+25\%\right):\dfrac{7}{5}\)
Giúp mình nha
Đang cần gấp
CMR \(1-\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{5}-\dfrac{1}{6}+...+\dfrac{1}{19}-\dfrac{1}{20}=\dfrac{1}{11}+\dfrac{1}{12}+\dfrac{1}{13}+...+\dfrac{1}{20}\)
