\(C=\dfrac{3}{14}:\dfrac{1}{28}-\dfrac{13}{21}:\dfrac{1}{28}-\dfrac{29}{42}:\dfrac{1}{28}-8\)
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23 tháng 9 2021
c: \(\dfrac{3}{14}:\dfrac{1}{28}-\dfrac{13}{21}:\dfrac{1}{28}\)
\(=28\left(\dfrac{3}{14}-\dfrac{13}{21}\right)\)
\(=28\cdot\left(\dfrac{9}{42}-\dfrac{26}{42}\right)\)
\(=28\cdot\dfrac{-17}{42}=\dfrac{-34}{3}\)
20 tháng 8 2017
a, \(4\dfrac{5}{37}\)-\(3\dfrac{4}{5}\)+ \(8\dfrac{15}{29}\)- \(3\dfrac{5}{37}\)+ \(6\dfrac{14}{29}\)
=(\(4\dfrac{5}{37}\)-\(3\dfrac{5}{37}\))+(\(8\dfrac{15}{29}\)+\(6\dfrac{14}{29}\))-\(3\dfrac{4}{5}\)
=(4-3)+(\(\dfrac{5}{37}\)-\(\dfrac{5}{37}\))+(8+6)+(\(\dfrac{15}{29}\)+\(\dfrac{14}{29}\))-3\(\dfrac{4}{5}\)
=1+ 15-\(3\dfrac{4}{5}\)=13-\(\dfrac{4}{5}\)=\(\dfrac{61}{5}\)
b, 60\(\dfrac{7}{13}\)+ 50\(\dfrac{8}{13}\)-11\(\dfrac{2}{13}\)
=(60+50-11)+(\(\dfrac{7}{13}\)+ \(\dfrac{8}{13}\)-\(\dfrac{2}{13}\))
=99+1=100
c, đáp án bằng \(\dfrac{-2}{3}\). bạn tự tính nha
PN
15 tháng 7 2017
1) \(\left(-1\dfrac{1}{5}+x\right):\left(-3\dfrac{3}{5}\right)=\dfrac{-7}{4}+\dfrac{1}{4}:\dfrac{1}{8}\)
\(\Leftrightarrow\left(-1\dfrac{1}{5}+x\right):\left(-3\dfrac{3}{5}\right)=\dfrac{-7}{4}+2\)
\(\Leftrightarrow\left(-1\dfrac{1}{5}+x\right):\left(-3\dfrac{3}{5}\right)=\dfrac{1}{4}\)
\(\Leftrightarrow-1\dfrac{1}{5}+x=\dfrac{1}{4}.\left(-3\dfrac{3}{5}\right)\)
\(\Leftrightarrow-1\dfrac{1}{5}+x=\dfrac{1}{4}.\left(-\dfrac{18}{5}\right)\)
\(\Leftrightarrow-1\dfrac{1}{5}+x=-\dfrac{9}{10}\)
\(\Leftrightarrow x=\left(-\dfrac{9}{10}\right)-\left(-1\dfrac{1}{5}\right)\)
\(\Leftrightarrow x=\dfrac{3}{10}\)
26 tháng 2 2022
\(a,\dfrac{1}{7}+\dfrac{1}{3}=\dfrac{3}{21}+\dfrac{7}{21}=\dfrac{10}{21}\\ b,\dfrac{-2}{3}+\dfrac{-5}{7}=\dfrac{-14+\left(-15\right)}{21}=\dfrac{-29}{21}\\ c,\dfrac{1}{2}-\dfrac{-1}{2}-\dfrac{1}{3}=\dfrac{3+3-2}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)
26 tháng 2 2022
\(a.\dfrac{4}{28}+\dfrac{12}{36}=\dfrac{1}{7}+\dfrac{1}{3}=\dfrac{3}{21}+\dfrac{7}{21}=\dfrac{10}{21}\\ b.\dfrac{-12}{18}+\dfrac{-15}{21}=\dfrac{-2}{3}+\dfrac{-5}{7}=\dfrac{-14}{21}+\dfrac{-15}{21}=\dfrac{-29}{21}\\ c.\dfrac{14}{28}+\dfrac{16}{32}-\dfrac{17}{51}=\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{17}{51}=1-\dfrac{17}{51}=\dfrac{2}{3}\)
TA
22 tháng 7 2021
a) `6/18+ (-14)/21 = 1/3 - 2/3=-1/3`
b) `3/5 - (-1/2) = 3/5+1/2=11/10`
c) `2/7 : 3/4 = 2/7 . 4/3 = 8/21`
d) `(-28)/33 . (-3)/4 = 28/33 . 3/4=7/11`
22 tháng 7 2021
a) \(\dfrac{6}{18}+\dfrac{-14}{21}=\dfrac{1}{3}-\dfrac{2}{3}=\dfrac{-1}{3}\)
b) \(\dfrac{3}{5}-\dfrac{-1}{2}=\dfrac{3}{5}+\dfrac{1}{2}=\dfrac{6}{10}+\dfrac{5}{10}=\dfrac{11}{10}\)
c) \(\dfrac{2}{7}:\dfrac{3}{4}=\dfrac{2}{7}\cdot\dfrac{4}{3}=\dfrac{8}{21}\)
d) \(\dfrac{-28}{33}\cdot\dfrac{-3}{4}=\dfrac{28}{4}\cdot\dfrac{3}{33}=7\cdot\dfrac{1}{11}=\dfrac{7}{11}\)
AT
12 tháng 7 2017
Theo quy ước với mọi phân số lớn hơn 0 thì ta có:
\(\dfrac{a}{b}>0=>\dfrac{a}{b}< \dfrac{a+n}{b+n}\left(n\in N;n\ne0\right)\)
Áp dụng với bài trên ta => ĐPCM
CHÚC BẠN HỌC TỐT.......
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
7 tháng 10 2023
Muốn làm những bài toán có chứa hỗn số thì em cần nhớ:
Bước 1: Chuyển các hỗn số có trong phép tính thành phân số.
Bước 2: Thực hiện phép tính theo thứ tự thực hiện phép tính
a, \(\dfrac{8\dfrac{1}{2}}{15:\dfrac{5}{17}}\)
= \(\dfrac{\dfrac{17}{2}}{15\times\dfrac{17}{5}}\)
= \(\dfrac{\dfrac{17}{2}}{3\times17}\)
= \(\dfrac{17}{2}\) x \(\dfrac{1}{3\times17}\)
= \(\dfrac{1}{6}\)
H
24 tháng 8 2023
a)
\(\dfrac{7}{24}+\dfrac{11}{6}\\ =\dfrac{7}{24}+\dfrac{11\times4}{6\times4}\\ =\dfrac{7}{24}+\dfrac{44}{24}\\ =\dfrac{7+44}{24}\\ =\dfrac{51}{24}\\=\dfrac{17}{8}\)
b)
\(3+\dfrac{5}{8}\\ =\dfrac{3\times8}{8}+\dfrac{5}{8}\\ =\dfrac{24}{8}+\dfrac{5}{8}\\ =\dfrac{29}{8}\)
c)
\(\dfrac{19}{28}-\dfrac{3}{7}\\ =\dfrac{19}{28}-\dfrac{3\times4}{7\times4}\\ =\dfrac{19}{28}-\dfrac{12}{28}\\ =\dfrac{7}{28}=\dfrac{1}{4}\)
d)
\(\dfrac{53}{21}-1\\ =\dfrac{53}{21}-\dfrac{21}{21}\\ =\dfrac{53-21}{21}\\ =\dfrac{32}{21}\)
GL
24 tháng 8 2023
a) \(\dfrac{7}{24}+\dfrac{11}{6}=\dfrac{7}{24}+\dfrac{44}{24}=\dfrac{7+44}{24}=\dfrac{51}{24}\)
b) \(3+\dfrac{5}{8}=\dfrac{24}{8}+\dfrac{5}{8}=\dfrac{24+5}{8}=\dfrac{29}{8}\)
c) \(\dfrac{19}{28}-\dfrac{3}{7}=\dfrac{19}{28}-\dfrac{12}{28}=\dfrac{19-12}{28}=\dfrac{7}{28}=\dfrac{1}{4}\)
d) \(\dfrac{53}{21}-1=\dfrac{53}{21}-\dfrac{21}{21}=\dfrac{53-21}{21}=\dfrac{32}{21}\)
\(=28\left(\dfrac{3}{14}-\dfrac{13}{21}-\dfrac{29}{42}\right)-8\\ =28\cdot\dfrac{-23}{21}-8=-\dfrac{92}{3}-8=-\dfrac{116}{3}\)
\(C=\dfrac{3}{14}:\dfrac{1}{28}-\dfrac{13}{21}:\dfrac{1}{28}-\dfrac{29}{42}:\dfrac{1}{28}-8\)
\(=28\left(\dfrac{3}{14}-\dfrac{13}{21}-\dfrac{29}{42}\right)-8\)
\(=28\left(\dfrac{9}{42}-\dfrac{26}{42}-\dfrac{29}{42}\right)-8\)
\(=28\cdot\dfrac{-46}{42}-8\)
\(=\dfrac{-116}{3}\)