B= \(\dfrac{1}{4}\)+\(\dfrac{1}{12}\)+\(\dfrac{1}{24}\)+....+\(\dfrac{1}{79600}\)
C= \(\dfrac{2}{5}\)+\(\dfrac{2}{45}\)+\(\dfrac{2}{117}\)+....+\(\dfrac{2}{6885}\)
Trình bày đầy đủ cả phép tính nha
Tks:3
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B= \(\dfrac{1}{4}\)+\(\dfrac{1}{12}\)+\(\dfrac{1}{24}\)+....+\(\dfrac{1}{79600}\)
\(\text{Thực hiện phép tính một cách hợp lí:}\)
\(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}\) \(\left(4-\dfrac{5}{12}\right):2+\dfrac{5}{24}\)
\(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}\)
=\(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}.\dfrac{5}{1}+\dfrac{3}{5}.\dfrac{1}{3}\)
=\(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{3}+\dfrac{3}{5}.\dfrac{1}{3}\)
=\(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{1}{3}.2+\dfrac{3}{5}.\dfrac{1}{3}\)
=\(\dfrac{1}{3}.\left(\dfrac{2}{5}+\dfrac{3}{5}-2\right)\)=\(\dfrac{1}{3}.\left(-1\right)=\dfrac{-1}{3}\)
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\(\left(4-\dfrac{5}{12}\right):2+\dfrac{5}{24}\)
=\(\left(4-\dfrac{5}{12}\right).\dfrac{1}{2}+\dfrac{5}{24}\)
=\(4.\dfrac{1}{2}-\dfrac{5}{12}.\dfrac{1}{2}+\dfrac{5}{24}\)
=\(2-\dfrac{5}{24}+\dfrac{5}{24}=2\)
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Giải:
\(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}\)
\(=\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{3}+\dfrac{3}{5}.\dfrac{1}{3}\)
\(=\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{1}{3}.2+\dfrac{3}{5}.\dfrac{1}{3}\)
\(=\dfrac{1}{3}.\left(\dfrac{2}{5}-2+\dfrac{3}{5}\right)\)
\(=\dfrac{1}{3}.\left(-1\right)\)
\(=\dfrac{-1}{3}\)
\(\left(4-\dfrac{5}{12}\right):2+\dfrac{5}{24}\)
\(=\dfrac{43}{12}:2+\dfrac{5}{24}\)
\(=\dfrac{43}{24}+\dfrac{5}{24}\)
\(=2\)
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Thực hiện phép tính-tính nhanh giá trị biểu thức
A19dfrac{1}{4} + dfrac{1}{2}x 2dfrac{1}{3}+5,75 - dfrac{1}{6}+74
B[(dfrac{1}{3}+dfrac{1}{4})] x dfrac{12}{19}+dfrac{12}{19}] : dfrac{4}{5}-dfrac{1}{4}+2012
Cdfrac{232323}{353535}:dfrac{76x47-28}{76x46+48}
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Thực hiện phép tính-tính nhanh giá trị biểu thức
A=19\(\dfrac{1}{4}\) + \(\dfrac{1}{2}\)x 2\(\dfrac{1}{3}\)+5,75 - \(\dfrac{1}{6}\)+74
B=[(\(\dfrac{1}{3}+\dfrac{1}{4}\))] x \(\dfrac{12}{19}+\dfrac{12}{19}\)] : \(\dfrac{4}{5}-\dfrac{1}{4}+2012\)
C=\(\dfrac{232323}{353535}:\dfrac{76x47-28}{76x46+48}\)
làm đầy đủ theo các bước nhé
Tìm x biết :
a) \(^{\dfrac{4}{9}+x=\dfrac{5}{3}}\)
b)\(\dfrac{3}{4}.x=\dfrac{-1}{2}\)
c) \(\dfrac{3}{7}+\dfrac{5}{7}:x=\dfrac{1}{3}\)
d)\(3\dfrac{1}{4}:\left|2x-\dfrac{5}{12}\right|=\dfrac{39}{16}\)
c.\(\dfrac{3}{7}+\dfrac{5}{7}:x=\dfrac{1}{3}\)
\(\dfrac{5}{7}:x=\dfrac{1}{3}-\dfrac{3}{7}\)
\(\dfrac{5}{7}:x=-\dfrac{2}{21}\)
\(x=\dfrac{5}{7}:-\dfrac{2}{21}\)
\(x=-\dfrac{15}{2}\)
d.\(3\dfrac{1}{4}:\left|2x-\dfrac{5}{12}\right|=\dfrac{39}{16}\)
\(\left|2x-\dfrac{5}{12}\right|=3\dfrac{1}{4}:\dfrac{39}{16}\)
\(\left|2x-\dfrac{5}{12}\right|=\dfrac{4}{3}\)
\(\rightarrow\left[{}\begin{matrix}2x-\dfrac{5}{12}=\dfrac{4}{3}\\2x-\dfrac{4}{12}=-\dfrac{4}{3}\end{matrix}\right.\) \(\rightarrow\left[{}\begin{matrix}2x=\dfrac{7}{4}\\2x=-\dfrac{11}{12}\end{matrix}\right.\) \(\rightarrow\left[{}\begin{matrix}x=\dfrac{7}{8}\\x=-\dfrac{11}{24}\end{matrix}\right.\)
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A, \(\dfrac{4}{9}+x=\dfrac{5}{3}\)
\(x\)\(=\dfrac{5}{3}-\dfrac{4}{9}\)
\(x\)\(=\dfrac{11}{9}\)
B,\(\dfrac{3}{4}.x=\dfrac{-1}{2}\)
\(x=\dfrac{-1}{2}:\dfrac{3}{4}\)
\(x=\)\(\dfrac{-2}{3}\)
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a)
\(\frac{4}{9} + x = \frac{5}{3}\)
=> \(x = \frac{5}{3}-\frac{4}{9}\)
=> \(x = \) \(\frac{11}{9}\)
Vậy \(x = \dfrac{11}{9}\)
b)
\(\dfrac{3}{4} .x = \dfrac{-1}{2}\)
=> \(x = \dfrac{-1}{2} : \dfrac{3}{4}\)
=> \(x = \dfrac{-2}{3}\)
Vậy \(x = \dfrac{-2}{3}\)
c)
\( \dfrac{3}{7}+ \dfrac{5}{7}:x = \dfrac{1}{3}\)
=> \(\dfrac{5}{7}:x = \dfrac{1}{3}-\) \( \dfrac{3}{7}\)
=> \(\dfrac{5}{7}:x = \dfrac{-2}{21}\)
=> \(x = \dfrac{5}{7}:\dfrac{-2}{21}\)
=> \(x = \dfrac{-15}{2}\)
Vậy \(x = \dfrac{-15}{2}\)
d)
\(3\dfrac{1}{4} : |2x - \dfrac{5}{12} | = \dfrac{39}{16}\)
=> \(\dfrac{13}{4} : |2x - \dfrac{5}{12} | = \dfrac{39}{16}\)
=> \( |2x - \dfrac{5}{12} | =\dfrac{13}{4} : \dfrac{39}{16}\)
=> \(|2x-\dfrac{5}{12} |= \dfrac{4}{3}\)
=> \(\left[\begin{matrix} 2x - \dfrac{5}{12} = \dfrac{4}{3}\\ 2x - \dfrac{5}{12} = \dfrac{4}{3}\end{matrix}\right.\)
=> \(\left[\begin{matrix} 2x = \dfrac{-4}{3}+\dfrac{5}{12}\\ 2x = \dfrac{-4}{3}+\dfrac{5}{12} \end{matrix}\right.\)
=> \(\left[\begin{matrix} 2x = \dfrac{7}{4}\\ 2x = \dfrac{-11}{12} \end{matrix}\right.\)
=> \(\left[\begin{matrix} x = \dfrac{7}{8}\\ x = \dfrac{-11}{24} \end{matrix}\right.\)
Vậy \(x \in \) { \(\dfrac{7}{8} ; \dfrac{-11}{24}\) }
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27 tháng 9 2021 lúc 6:38
Bài 1 : Thực hiện phép tính a/ dfrac{7}{6} - dfrac{13}{12} + dfrac{3}{4}b/ 1 dfrac{1}{2} . dfrac{-4}{5} + dfrac{3}{10}c/ dfrac{25}{9} . dfrac{3}{10} + ( dfrac{-5}{3} )^2 . dfrac{7}{10} + | dfrac{-25}{3} | Bài 2 : Tìm x , biếta/ x - dfrac{5}{6} dfrac{1}{4}b/ dfrac{26}{x} dfrac{-13}{-15}( Cần gấp )
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Bài 1 : Thực hiện phép tính
a/ \(\dfrac{7}{6}\) - \(\dfrac{13}{12}\) + \(\dfrac{3}{4}\)
b/ 1 \(\dfrac{1}{2}\) . \(\dfrac{-4}{5}\) + \(\dfrac{3}{10}\)
c/ \(\dfrac{25}{9}\) . \(\dfrac{3}{10}\) + ( \(\dfrac{-5}{3}\) )\(^2\) . \(\dfrac{7}{10}\) + | \(\dfrac{-25}{3}\) |
Bài 2 : Tìm x , biết
a/ x - \(\dfrac{5}{6}\) = \(\dfrac{1}{4}\)
b/ \(\dfrac{26}{x}\) = \(\dfrac{-13}{-15}\)
( Cần gấp )
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) Ta có: \(\dfrac{-5}{18}+\dfrac{32}{45}-\dfrac{9}{10}\)
\(=\dfrac{-25}{90}+\dfrac{64}{90}-\dfrac{81}{90}\)
\(=\dfrac{-42}{90}=-\dfrac{7}{15}\)
b) Ta có: \(\left(-\dfrac{1}{4}+\dfrac{51}{33}-\dfrac{5}{3}\right)-\left(-\dfrac{15}{12}+\dfrac{6}{11}-\dfrac{42}{29}\right)\)
\(=\dfrac{-1}{4}+\dfrac{17}{11}-\dfrac{5}{3}+\dfrac{5}{4}-\dfrac{6}{11}+\dfrac{42}{29}\)
\(=\dfrac{-5}{3}+\dfrac{42}{29}\)
\(=\dfrac{-145}{87}+\dfrac{126}{87}=\dfrac{-19}{87}\)
c) Ta có: \(1-\dfrac{1}{2}+2-\dfrac{2}{3}+3-\dfrac{3}{4}+4-\dfrac{1}{4}-3-\dfrac{1}{3}-2-\dfrac{1}{2}-1\)
\(=\left(1-1\right)-\left(\dfrac{1}{2}+\dfrac{1}{2}\right)+\left(2-2\right)-\left(\dfrac{2}{3}+\dfrac{1}{3}\right)+\left(3-3\right)-\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+4\)
\(=-1-1-1+4\)
=1
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a) Ta có: =−2590+6490−8190=−2590+6490−8190
(−14+5133−53)−(−1512+611−4229)(−14+5133−53)−(−1512+611−4229)
=−53+4229=−53+4229
1−12+2−23+3−34+4−14−3−13−2−12−11−12+2−23+3−34+4−14−3−13−2−12−1
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Tính (Tính hợp lí nếu có thể)a) dfrac{-7}{12}-dfrac{3}{36}b) (4-dfrac{5}{12}):2+dfrac{5}{24}c) dfrac{8}{9}+dfrac{1}{9}.dfrac{2}{13}+dfrac{1}{9}.dfrac{11}{13}d) dfrac{3}{4}.dfrac{8}{9}.dfrac{15}{16}. ... .dfrac{9999}{10000}e) dfrac{3}{1.4}+dfrac{3}{4.7}+dfrac{3}{7.10}+...+dfrac{3}{97.100}*Lưu ý: Mong các anh chị trình bày chi tiết để em có thể hiểu bài, em xin các anh chị đừng viết mỗi kết quả xong em chả biết một cái gì ;-;
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Tính (Tính hợp lí nếu có thể)
a) \(\dfrac{-7}{12}\)-\(\dfrac{3}{36}\)
b) (4-\(\dfrac{5}{12}\)):2+\(\dfrac{5}{24}\)
c) \(\dfrac{8}{9}\)+\(\dfrac{1}{9}\).\(\dfrac{2}{13}\)+\(\dfrac{1}{9}\).\(\dfrac{11}{13}\)
d) \(\dfrac{3}{4}\).\(\dfrac{8}{9}\).\(\dfrac{15}{16}\). ... .\(\dfrac{9999}{10000}\)
e) \(\dfrac{3}{1.4}\)+\(\dfrac{3}{4.7}\)+\(\dfrac{3}{7.10}\)+...+\(\dfrac{3}{97.100}\)
*Lưu ý: Mong các anh chị trình bày chi tiết để em có thể hiểu bài, em xin các anh chị đừng viết mỗi kết quả xong em chả biết một cái gì ;-;
a: =-21/36-3/36=-24/36=-2/3
b: =43/12*1/2+5/24=43/24+5/24=2
c: =8/9+1/9=1
e: =1-1/4+1/4-1/7+...+1/97-1/100
=1-1/100=99/100
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Thực hiện phép tính, tính nhanh nếu có thểa, dfrac{7}{13} + dfrac{12}{13} + dfrac{6}{-13}b, ( dfrac{4}{5} + dfrac{1}{2} ) x ( dfrac{6}{13} - 2 )c, 75% : dfrac{1}{2} - 2dfrac{1}{2} x ( -1dfrac{1}{3} )d, 0,375 x 1dfrac{3}{5} + 60% x dfrac{2}{7} + dfrac{3}{5} x dfrac{5}{7}e, dfrac{-5}{6} x dfrac{7}{13} + dfrac{19}{13} : dfrac{6}{-5} + dfrac{2}{5}f, 1,25 x dfrac{7}{9}+dfrac{5}{4}xdfrac{15}{9}-1dfrac{1}{4}:dfrac{19}{3}
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Thực hiện phép tính, tính nhanh nếu có thể
a, \(\dfrac{7}{13}\) + \(\dfrac{12}{13}\) + \(\dfrac{6}{-13}\)
b, ( \(\dfrac{4}{5}\) + \(\dfrac{1}{2}\) ) x ( \(\dfrac{6}{13}\) - 2 )
c, 75% : \(\dfrac{1}{2}\) - \(2\dfrac{1}{2}\) x ( \(-1\dfrac{1}{3}\) )
d, 0,375 x \(1\dfrac{3}{5}\) + 60% x \(\dfrac{2}{7}\) + \(\dfrac{3}{5}\) x \(\dfrac{5}{7}\)
e, \(\dfrac{-5}{6}\) x \(\dfrac{7}{13}\) + \(\dfrac{19}{13}\) : \(\dfrac{6}{-5}\) + \(\dfrac{2}{5}\)
f, 1,25 x \(\dfrac{7}{9}+\dfrac{5}{4}x\dfrac{15}{9}-1\dfrac{1}{4}:\dfrac{19}{3}\)
a: \(=\dfrac{7+12-6}{13}=1\)
b: \(=\dfrac{13}{10}\cdot\dfrac{6-26}{13}=\dfrac{-20}{10}=-2\)
c: \(=\dfrac{3}{4}\cdot2-\dfrac{5}{2}\cdot\dfrac{-4}{3}=\dfrac{3}{2}+\dfrac{20}{6}=\dfrac{3}{2}+\dfrac{10}{3}=\dfrac{29}{6}\)
d: \(=\dfrac{3}{8}\cdot\dfrac{8}{5}+\dfrac{3}{5}\cdot\dfrac{2}{7}+\dfrac{3}{5}\cdot\dfrac{5}{7}=\dfrac{3}{5}+\dfrac{3}{5}=\dfrac{6}{5}\)
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Bài 4. Trên tia Ox lấy điểm A và B sao cho OA = 8cm, OB = 12cm.
a, Điểm A có nằm giữa hai điểm O và B không? Vì sao? Tính AB.
b, Gọi M, N lần lượt là trung điểm của OA, OB. Điểm M có nằm giữa hai điểm O và N không? Vì sao? Tính MN.
c, Điểm N có là trung điểm của đoạn thẳng AM không? Vì sao?
cho mìn hỏi câu b nhoa
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1.Thực hiện các phép tính sau :
a) \(-\dfrac{4}{3}.\dfrac{5}{12}+\dfrac{1}{3}.\dfrac{5}{12}\) b)\(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right):\dfrac{3}{28}\)
2.Tìm x, biết:
a) 2x+19=\(^{5^2}\) b)\(-\dfrac{2}{9}x-\dfrac{1}{7}=\dfrac{4}{21}\)
1,
a, \(\left(\dfrac{-4}{3}+\dfrac{1}{3}\right).\dfrac{5}{12}\)=-\(\dfrac{5}{12}\)
b, \(\dfrac{16}{5}+\left(\dfrac{-45}{14}\right):\dfrac{3}{28}\)
=\(\dfrac{-2}{15}\)
2,
a, 2x+19=25
=>x=3
b, \(-\dfrac{2}{9}x=\dfrac{1}{3}\)
=>x=\(\dfrac{-3}{2}\)
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Bài 1:
a) Ta có: \(\dfrac{-4}{3}\cdot\dfrac{5}{12}+\dfrac{1}{3}\cdot\dfrac{5}{12}\)
\(=\dfrac{5}{12}\cdot\left(\dfrac{-4}{3}+\dfrac{1}{3}\right)\)
\(=\dfrac{-5}{12}\)
b) Ta có: \(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right):\dfrac{3}{28}\)
\(=\dfrac{16}{5}+\left(\dfrac{4}{14}-\dfrac{49}{14}\right):\dfrac{3}{28}\)
\(=\dfrac{16}{5}+\dfrac{-45}{14}\cdot\dfrac{28}{3}\)
\(=\dfrac{16}{5}-30=\dfrac{-134}{5}\)
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1)
a) \(-\dfrac{4}{3}.\dfrac{5}{12}+\dfrac{1}{3}.\dfrac{5}{12}=\dfrac{5}{12}.\left(\dfrac{-4}{3}+\dfrac{1}{3}\right)=\dfrac{5}{12}.\left(-1\right)=-\dfrac{5}{12}\)
b) \(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right).\dfrac{28}{3}=3+\dfrac{1}{5}-\dfrac{45}{14}.\dfrac{28}{3}\)
\(=3+\dfrac{1}{5}-30=-27+\dfrac{1}{5}=-\dfrac{134}{5}\)
2)
a) \(2x+19=25\)
\(2x=25-19=6\)
\(x=3\)
b) \(-\dfrac{2}{9}x-\dfrac{1}{7}=\dfrac{4}{21}\)
\(-\dfrac{2x}{9}=\dfrac{4}{21}+\dfrac{1}{7}=\dfrac{1}{3}\)
\(x=\dfrac{1}{3}.\left(-\dfrac{9}{2}\right)=-\dfrac{3}{2}\)
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