\(9\frac{7}{5}+9,4=?\)
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Trong các phân số 5/7,8/9,4/7,7/9 phân số bé nhất là :
A. 5/7
B. 8/9
C.4/7
D. 7/9
Hoktot
Bài làm
9,4 × 90 + 9 × 9,4 + 9,4
= 9,4 x ( 90 + 9 + 1 )
= 9,4 x 100
= 940
# Chúc bạn học tốt #
\(A=\dfrac{1}{3}-\dfrac{3}{5}+\dfrac{5}{7}-\dfrac{7}{9}+\dfrac{9}{11}-\dfrac{11}{13}-\dfrac{9}{11}+\dfrac{7}{9}-\dfrac{5}{7}+\dfrac{3}{5}-\dfrac{1}{3}\\ \Leftrightarrow A=\dfrac{1}{3}-\dfrac{1}{3}-\dfrac{3}{5}+\dfrac{3}{5}+\dfrac{5}{7}-\dfrac{5}{7}-\dfrac{7}{9}+\dfrac{7}{9}+\dfrac{9}{11}-\dfrac{9}{11}-\dfrac{11}{13}\\ \Leftrightarrow A=\left(\dfrac{1}{3}-\dfrac{1}{3}\right)-\left(\dfrac{3}{5}-\dfrac{3}{5}\right)+\left(\dfrac{5}{7}-\dfrac{5}{7}\right)-\left(\dfrac{7}{9}-\dfrac{7}{9}\right)+\left(\dfrac{9}{11}-\dfrac{9}{11}\right)-\dfrac{11}{13}\\ \Leftrightarrow A=0-0+0-0+0-\dfrac{11}{13}\\ \Leftrightarrow A=\dfrac{-11}{13}\)
\(\frac{5}{7}.\frac{5}{9}+\frac{5}{7}.\frac{2}{9}-\frac{5}{7}.\frac{14}{9}\)
\(=\frac{5}{7}.\left(\frac{5}{9}+\frac{2}{9}-\frac{14}{9}\right)\)
\(=\frac{5}{7}.\frac{-7}{9}\)
\(=\frac{-5}{9}\)
\(\frac{5}{7}\cdot\frac{5}{9}+\frac{5}{7}\cdot\frac{2}{9}-\frac{5}{7}\cdot\frac{14}{9}\)
\(=\frac{5}{7}.\left(\frac{5}{9}+\frac{2}{9}-\frac{14}{9}\right)\)
\(=\frac{5}{7}\cdot-\frac{7}{9}\)
\(=-\frac{5}{9}\)
\(N=\frac{1}{6}.\frac{5}{9}+\frac{5}{9}.\frac{2}{7}+\frac{1}{9}.\frac{5}{7}-\frac{5}{9}.\frac{3}{7}\)
\(N=\frac{1}{6}.\left(\frac{5}{9}+\frac{1}{9}\right).\left(\frac{2}{7}+\frac{5}{7}-\frac{3}{7}\right)\)
\(N=\frac{1}{6}.\frac{6}{9}.\frac{4}{7}\)
\(N=\frac{1}{9}.\frac{4}{7}\)
\(N=\frac{4}{63}\)
\(N=\frac{1}{6}.\frac{5}{9}+\frac{5}{9}.\frac{2}{7}+\frac{1}{9}.\frac{5}{7}-\frac{5}{9}.\frac{3}{7}\)
\(N=\frac{1}{6}.\frac{5}{9}+\frac{5}{9}.\frac{2}{7}+\frac{5}{9}.\frac{1}{7}-\frac{5}{9}.\frac{3}{7}\)
\(N=\frac{5}{9}.\left(\frac{1}{6}+\frac{2}{7}+\frac{1}{7}-\frac{3}{7}\right)\)
\(N=\frac{5}{9}.\frac{1}{6}\)
\(N=\frac{5}{54}\)
= 1/3 - 1/3 + 5/7 - 5/7 - 7/9 + 7/9 +9/11 - 9/11 -11/13 + 11/13 +13/15
= 0 + 0 - 0 + 0 -0 + 13/15
= 0 + 13/15
= 13/15
\(\frac{1}{3}-\frac{3}{5}+\frac{5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}+\frac{13}{15}+\frac{11}{13}-\frac{9}{11}+\frac{7}{9}-\frac{5}{7}+\frac{3}{5}-\frac{1}{3}\)
\(=\left(\frac{1}{3}-\frac{1}{3}\right)+\left(\frac{3}{5}-\frac{3}{5}\right)+\left(\frac{5}{7}-\frac{5}{7}\right)+\left(\frac{7}{9}-\frac{7}{9}\right)+\left(\frac{9}{11}-\frac{9}{11}\right)+\left(\frac{11}{13}-\frac{11}{13}\right)+\frac{13}{15}\)
\(=0+0+0+0+0+0+\frac{13}{15}\)
\(=\frac{13}{15}\)
= 19,8 bạn ạ