Chọn C

C là phương án đúng nhất

Chọn B

đáp án : B

1. \(\frac{2016}{2017}\)+\(\frac{2017}{2018}\)>1

2. A>B

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 \(4\frac{1}{5}:3\frac{6}{7}=\frac{21}{5}:\frac{27}{7}=\frac{21}{5}.\frac{7}{27}=\frac{147}{135}\)

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 

1. a) \(\frac{-2}{7}+\frac{15}{23}+\frac{\left(-15\right)}{17}+\frac{4}{19}+\frac{8}{23}\)

    \(=\left(\frac{-2}{7}+\frac{-5}{7}\right)+\left(\frac{15}{23}+\frac{8}{23}\right)+\frac{4}{19}\)

    \(=\left(-1\right)+1+\frac{4}{19}\)

    \(=0+\frac{4}{19}=\frac{4}{19}\)

b) \(\frac{7}{19}\cdot\frac{8}{11}+\frac{7}{19}\cdot\frac{3}{11}+\frac{12}{19}\)

   \(=\frac{7}{19}\cdot\left(\frac{8}{11}+\frac{3}{11}\right)+\frac{12}{19}\)

   \(=\frac{7}{19}\cdot1+\frac{12}{19}\)

   \(=\frac{7}{19}+\frac{12}{19}=\frac{19}{19}=1\)

2. a) \(\frac{1}{3}+\frac{\left(-2\right)}{16}-\frac{7}{14}\)

\(=\frac{5}{24}-\frac{1}{2}\)

\(=-\frac{7}{24}\)

b) \(11\frac{3}{13}-2\frac{4}{7}+5\frac{3}{13}\)

\(=\left(11-2+5\right)+\frac{3}{13}-\frac{4}{7}+\frac{3}{13}\)

\(=14+\left(-\frac{10}{91}\right)\)

\(=-14\frac{10}{91}\)

c) \(0,7\cdot2\frac{2}{3}\cdot20\cdot0,375\cdot\frac{5}{28}\)

\(=\frac{7}{10}\cdot\frac{8}{3}\cdot20\cdot\frac{3}{8}\cdot\frac{5}{28}\)

\(=\left(\frac{7}{10}\cdot\frac{5}{28}\right)\cdot\left(\frac{8}{3}\cdot\frac{3}{8}\right)\cdot20\)

\(=\frac{1}{8}\cdot1\cdot20\)

\(=\frac{20}{8}=\frac{5}{2}\)

d) \(\frac{6}{7}+\frac{5}{7}:5-\frac{8}{9}\)

\(=\frac{6}{7}+\frac{1}{7}-\frac{8}{9}\)

\(=1-\frac{8}{9}\)

\(=\frac{1}{9}\)

~Học tốt~