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Bài 2: Mỗi xe ô tô có 4 bánh xe . Hỏi 5 xe ô tô như thế có bao nhiêu bánh xe ?
Bài giải
5 xe ô tô như thế có số bánh xe là :
4 x 5= 20 (bánh xe )
Đáp số : 20 bánh xe
\(C=\frac{8}{9}.\frac{15}{16}.\frac{24}{25}.........\frac{2499}{2500}\)
\(=\frac{2.4}{3^2}.\frac{3.5}{4^2}.\frac{4.6}{5^2}......\frac{49.51}{50^2}\)
\(=\frac{2.3.4....49}{3.4.5....50}.\frac{4.5.6....51}{3.4.5....50}\)
\(=\frac{1}{25}.17=\frac{17}{25}\)
\(a)\) \(A=\left(1-\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right).....\left(1-\frac{1}{1000}\right)\)
\(A=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.....\frac{999}{1000}\)
\(A=\frac{1.2.3.....999}{2.3.4.....1000}\)
\(A=\frac{1}{1000}.\frac{2.3.4.....999}{2.3.4.....999}\)
\(A=\frac{1}{1000}\)
Vậy \(A=\frac{1}{1000}\)
a)\(\frac{-5}{13}+\left(\frac{3}{5}+\frac{3}{13}-\frac{4}{10}\right)=\frac{-5}{13}-\frac{3}{5}-\frac{3}{13}+\frac{4}{10}=\left(\frac{-5}{13}-\frac{3}{13}\right)+\frac{4}{10}-\frac{3}{5}=\frac{-5-3}{13}+\left(\frac{4}{10}-\frac{6}{10}\right)=\frac{-8}{13}+\frac{-2}{10}=\frac{-80}{130}+\frac{-26}{130}=\frac{-106}{130}=\frac{-53}{65}\)
Bài 1:
a) \(\frac{\left(-3\right)}{16}+\frac{1}{15}=\frac{-45}{240}+\frac{16}{240}\)
\(=\frac{-29}{240}\)
b)\(\frac{\left(-15\right)}{24}-\frac{\left(-2\right)}{6}=\frac{\left(-15\right)}{24}-\frac{-8}{24}\)
\(=\frac{-7}{24}\)
c) \(\frac{\left(-16\right)}{18}\cdot\frac{36}{\left(-40\right)}=\frac{\left(-8\right)}{9}\cdot\frac{\left(-9\right)}{10}\)
\(=\frac{\left(-80\right)}{90}\cdot\frac{\left(-81\right)}{90}\)
\(=\frac{4}{5}\)
d)\(\frac{\left(-17\right)}{30}:\frac{34}{60}=\frac{\left(-17\right)}{30}:\frac{17}{30}\)
\(=\frac{\left(-17\right)}{30}\cdot\frac{30}{17}\)
\(=-1\)
Bài 2:
a) \(1\frac{3}{5}+2\frac{1}{6}=\frac{8}{5}+\frac{13}{6}=\frac{48}{30}+\frac{65}{30}\)
\(=\frac{113}{30}\)
b) \(3\frac{1}{7}-1\frac{1}{8}=\frac{22}{7}-\frac{9}{8}=\frac{176}{56}-\frac{63}{56}\)
\(=\frac{113}{56}\)
c) \(3\frac{1}{6}\cdot2\frac{1}{4}=\frac{19}{6}\cdot\frac{9}{4}=\frac{57}{8}\)
d) \(4\frac{1}{5}:3\frac{6}{7}=\frac{21}{5}:\frac{27}{7}=\frac{21}{5}\cdot\frac{7}{27}\)
\(=\frac{49}{45}\)
a \(\frac{-3}{16}+\frac{1}{15}=\frac{-45}{240}+\frac{16}{240}=\frac{-29}{240}\)
b \(\frac{-15}{24}-\frac{-2}{6}=\frac{-15}{24}-\frac{-8}{24}=\frac{-7}{24}\)
c \(\frac{-16}{18}.\frac{36}{-40}=\frac{4}{5}\)
d \(\frac{-17}{30}:\frac{34}{60}=\frac{-17}{30}.\frac{60}{34}=-1\)
bai 2
\(1\frac{3}{5}+2\frac{1}{6}=\frac{8}{5}+\frac{13}{6}=\frac{113}{30}\)
\(3\frac{1}{7}-1\frac{1}{8}=\frac{22}{7}-\frac{9}{8}=\frac{113}{56}\)
c \(3\frac{1}{6}.2\frac{1}{4}=\frac{19}{6}.\frac{9}{4}=\frac{57}{8}\)
d \(4\frac{1}{5}:3\frac{6}{7}=\frac{21}{5}:\frac{27}{7}=\frac{21}{5}.\frac{7}{27}=\frac{147}{135}\)