\(A=\)\(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{5}\)
\(B=\frac{2}{5}.\frac{15}{4}:\frac{5}{16}+\frac{1}{2}\)
tính giá trị biểu thức
\(A=\frac{-378.132+189.64}{15+18+21+......+45+48}\)
\(B=1,4.\frac{15}{14}-\left(\frac{4}{5}+\frac{2}{5}\right):2\frac{1}{5}-\frac{\frac{73}{77}+\frac{73}{165}+\frac{73}{285}}{\frac{25}{24}+\frac{15}{180}+\frac{20}{285}}\)
\(C=\frac{7+\frac{7}{12}-\frac{7}{144}+\frac{7}{60}}{5+\frac{6}{12}-\frac{5}{144}}.\frac{\frac{3}{4}-\frac{3}{16}+\frac{3}{64}-\frac{3}{256}}{1-\frac{1}{4}+\frac{1}{16}-\frac{1}{34}}-\frac{1}{20}\)
\(A=\frac{1}{3}-\frac{3}{4}-\left(-\frac{3}{5}\right)+\frac{1}{72}-\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)\(\frac{1}{15}\)
\(B=\frac{1}{5}-\frac{3}{7}+\frac{5}{9}-\frac{2}{11}+\frac{7}{13}-\frac{9}{16}-\frac{7}{13}+\frac{2}{11}-\frac{5}{9}+\frac{3}{7}-\frac{1}{5}\)
a, \(5\frac{4}{13}.15\frac{3}{41}-5\frac{4}{13}.2\frac{3}{41}\)
b, \(6.(-\frac{1}{3})^2-(\frac{1}{4}:2-\frac{7}{16}.\frac{-4}{21})\)
Thực hiện phép tính ( bằng cách hợp lí nếu có thể):
a, \(5\frac{4}{13}.15\frac{3}{41}-5\frac{4}{13}.2\frac{3}{41}\)
\(=5\frac{4}{13}\left(15\frac{3}{41}-2\frac{3}{41}\right)\)
\(=15\frac{4}{13}\left(\frac{618}{41}-\frac{85}{41}\right)\)
\(=\frac{69}{13}.13\)
\(=69\)
b, \(6.\left(-\frac{1}{3}\right)^2-\left(\frac{1}{4}:2-\frac{7}{16}.\frac{-4}{21}\right)\)
\(=6.\frac{1}{9}-\left(\frac{1}{8}-\frac{-1}{12}\right)\)
\(=\frac{2}{3}-\left(\frac{3}{24}-\frac{-2}{24}\right)\)
\(=\frac{2}{3}-\frac{5}{24}\)
\(=\frac{16}{24}-\frac{5}{24}\)
\(=\frac{11}{24}\)
Chúc bạn hok tốt!!! lưu khánh huyền
bài này đề bài là :thực hiện phép tính(bằng cách hợp lí nếu có thể):
a)\(5\frac{4}{3}.15\frac{3}{41}-5\frac{4}{13}.2\frac{3}{41}\)
=\(5\frac{4}{13}.\left(15\frac{3}{41}-2\frac{3}{41}\right)\)
=\(5\frac{4}{13}.13\)
=69
Tính giá trị biểu thức
\(1.A=\frac{1}{5}+\frac{3}{17}-\frac{4}{3}+\left(\frac{4}{5}-\frac{3}{17}+\frac{1}{3}\right)-\frac{1}{7}+\left[\frac{-14}{30}\right]\)
\(2.B=\left(\frac{5}{8}-\frac{4}{12}+\frac{3}{2}\right)-\left(\frac{5}{8}+\frac{9}{13}\right)-\left[\frac{-3}{2}\right]+\frac{7}{-15}\)
\(3.C=\frac{5}{18}+\frac{8}{19}-\frac{7}{21}+\left(\frac{-10}{36}+\frac{11}{19}+\frac{1}{3}\right)-\frac{5}{8}\)
\(4.D=\frac{1}{9}-\left[\frac{-5}{23}\right]-\left(\frac{-5}{23}+\frac{1}{9}+\frac{25}{7}\right)+\frac{50}{14}-\frac{7}{30}\)
\(5.E=\frac{1}{13}+\left(\frac{-5}{18}-\frac{1}{13}+\frac{12}{17}\right)+\left(\frac{12}{17}+\frac{5}{18}+\frac{7}{5}\right)\)
\(6.F=\frac{15}{14}-\left(\frac{17}{23}-\frac{80}{87}+\frac{5}{4}\right)+\left(\frac{12}{17}-\frac{15}{14}+\frac{1}{4}\right)\)
\(7.G=\frac{1}{25}-\frac{4}{27}+\left(\frac{-23}{27}+\frac{-1}{25}-\frac{5}{43}\right)+\frac{5}{43}-\frac{4}{7}\)
\(8.H=\frac{4}{15}-\frac{23}{28}-\left(\frac{-23}{28}+\frac{-11}{15}-\frac{29}{27}\right)-\frac{2}{27}\)
\(9.K=\frac{1}{16}-\frac{5}{21}+\left(\frac{-1}{16}+\frac{-3}{5}-\frac{-5}{21}\right)+\frac{-2}{5}+\frac{3}{4}\)
\(10.L=\frac{7}{12}+\frac{15}{14}-\left(\frac{14}{22}+\frac{-1}{14}+\frac{5}{21}\right)-\frac{-5}{21}+\frac{3}{5}\)
yutyugubhujyikiu
bài 1 : tính phân số:
a) \(\frac{5}{7}+\frac{4}{9}=?;\frac{4}{5}-\frac{2}{3}=?;\frac{9}{11}+\frac{3}{8}=?;\frac{16}{25}-\frac{2}{5}=?\)=?
b)\(5+\frac{3}{5}=?;10-\frac{9}{16}=?;\frac{2}{3}-\left(\frac{1}{6}+\frac{1}{8}\right)=?\)
c)\(\frac{5}{7}+\frac{7}{6}=?;\frac{7}{12}+\frac{17}{18}=?;\frac{9}{8}+\frac{15}{32}=?;4+\frac{35}{45}=?\)
d)\(\frac{11}{4}-\frac{15}{16}=?;\frac{5}{6}-\frac{5}{8}=?;\frac{196}{64}-2=?;3-\frac{13}{9}=?\)
e)\(\frac{8}{5}+\frac{7}{6}+\frac{5}{9}-2=?;3-\frac{5}{6}-\frac{4}{9}+\frac{32}{24}=?\)
a)\(\dfrac{5}{7}+\dfrac{4}{9}=\dfrac{45}{63}+\dfrac{28}{63}=\dfrac{73}{63}\) ; \(\dfrac{9}{11}+\dfrac{3}{8}=\dfrac{72}{88}+\dfrac{33}{88}=\dfrac{105}{88}\)
\(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\); \(\dfrac{16}{25}-\dfrac{2}{5}=\dfrac{16}{25}-\dfrac{10}{25}=\dfrac{6}{25}\)
Chứng minh rằng:
a. \(\frac{1}{3^2}+\frac{2}{3^3}+\frac{3}{3^4}+\frac{4}{3^5}+...+\frac{99}{3^{100}}+\frac{100}{3^{101}}< \frac{1}{4}\)
b.\(\frac{1}{2}-\frac{1}{4}+\frac{1}{8}-\frac{1}{16}+\frac{1}{32}-\frac{1}{64}< \frac{1}{3}\)
c.\(\frac{1}{3}-\frac{2}{3^2}+\frac{3}{3^3}-\frac{4}{3^4}+...+\frac{99}{3^{99}}-\frac{100}{3^{100}}< \frac{1}{16}\)
d. \(\frac{1}{5^2}-\frac{2}{5^3}+\frac{3}{5^4}-\frac{4}{5^5}+...+\frac{99}{5^{100}}-\frac{100}{5^{101}}< \frac{1}{36}\)
Tính nhanh:
a) A=\(\frac{1}{3}-\frac{3}{4}-\left(-\frac{3}{5}\right)+\frac{1}{72}-\frac{2}{9}-\frac{1}{36}+\frac{2}{15}\)b) B=\(\frac{1}{5}-\frac{3}{7}+\frac{5}{9}-\frac{2}{11}+\frac{7}{13}-\frac{9}{16}-\frac{7}{13}+\frac{2}{11}-\frac{5}{9}+\frac{3}{7}-\frac{1}{5}\)c) C= \(\frac{1}{100}-\frac{1}{100.99}-\frac{1}{99.98}-...-\frac{1}{3.2}-\frac{1}{2.1}\)Tính:
\(\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}+\frac{1}{7}-\frac{1}{8}+.....+\frac{1}{2015}-\frac{1}{2016}+\frac{1}{2017}.\)
\(\frac{5-\frac{5}{3}+\frac{5}{9}-\frac{5}{27}}{8-\frac{8}{3}+\frac{8}{9}-\frac{8}{27}}:\frac{15-\frac{15}{11}+\frac{15}{121}}{16-\frac{16}{11}+\frac{16}{121}}.\)
TÍNH NHANH:
\(A=\frac{1}{3}-\frac{3}{4}-\left(-\frac{3}{5}\right)+\frac{1}{72}-\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)
\(B=\frac{1}{5}-\frac{3}{7}+\frac{5}{9}-\frac{2}{11}+\frac{7}{13}-\frac{9}{16}-\frac{7}{13}+\frac{2}{11}-\frac{5}{9}+\frac{3}{7}-\frac{1}{5}\)
A= 1/3- 3/4+ 3/5+ 1/72- 2/9- 1/36+ 1/15
A= ( 1/3- 3/5+ 1/15) - (3/4- 1/72+ 2/9+ 1/36)
A= (5/15- 9/15+ 1/15) - (54/72- 1/72+ 16/72+ 2/36)
A= 1- 71/72
A= 1/72
A = \(\frac{1}{3}\)- \(\frac{3}{4}\) - ( - \(\frac{3}{5}\)) + \(\frac{1}{72}\)- \(\frac{2}{9}\)- \(\frac{1}{36}\)+ \(\frac{1}{15}\)
A = ( \(\frac{1}{3}\)+ \(\frac{3}{5}\)+ \(\frac{1}{15}\)) - ( \(\frac{3}{4}\)- \(\frac{1}{72}\)+ \(\frac{2}{9}\)+ \(\frac{1}{36}\))
A = ( \(\frac{5}{15}\)+ \(\frac{9}{15}\)+ \(\frac{1}{15}\)) - ( \(\frac{54}{72}\)- \(\frac{1}{72}\)+ \(\frac{16}{72}\)+ \(\frac{2}{72}\))
A = 1 - \(\frac{71}{72}\)
A = \(\frac{1}{72}\)