a)\(\frac{2}{7}+\frac{3}{8}=\frac{16}{56}+\frac{21}{56}=\frac{37}{56}\)
b)\(\frac{7}{56}:\frac{20}{25}=\frac{6}{56}x\frac{25}{20}=\frac{150}{1120}=\frac{15}{112}\)
c)\(\frac{20}{35}x\frac{5}{4}=\frac{100}{140}=\frac{5}{7}\)
d)\(\frac{8}{7}-\frac{5}{6}=\frac{48}{56}-\frac{35}{56}=\frac{13}{56}\)
thực hiện phép tính :
a ) \(\frac{1}{2}.\left(\frac{2}{9}+\frac{3}{7}-\frac{5}{27}\right)\)
b )( \(\frac{-5}{28}+1,75+\frac{8}{35}\)) : \(\left(-3\frac{9}{20}\right)\)
c ) \(\frac{1}{3}.\frac{5}{7}-\frac{7}{27}.\frac{36}{14}\)
d ) \(70,5-528:\frac{15}{2}\)
Tìm tập hợp các số x thuộc N sao cho
\(\frac{2}{3}+\frac{4}{35}< \frac{x}{105}< \frac{1}{7}+\frac{2}{5}+\frac{1}{3}\)
Tìm tập hợp x thuộc Z biết rằng:
\(\frac{-7}{15}+\frac{8}{60}+\frac{24}{90}< hoăc=\frac{x}{15}< hoặc=\frac{3}{5}+\frac{8}{30}+\frac{-4}{10}\)
tìm x biết :
a) \(\left(x+\frac{1}{2}\right).\left(\frac{2}{3}-2x\right)=0\)
b) \(\left(x.6\frac{2}{7}+\frac{3}{7}\right).2\frac{1}{5}-\frac{3}{7}=-2\)
c) \(x.3\frac{1}{4}+\left(-\frac{7}{6}\right).x-1\frac{2}{3}=\frac{5}{12}\)
d) \(5\frac{8}{17}:x+\left(-\frac{4}{17}\right):x+3\frac{1}{7}:17\frac{1}{3}=\frac{4}{11}\)
e) \(\frac{17}{2}-\left|2x-\frac{3}{4}\right|=-\frac{7}{4}\)
tìm x biết :
a) \(\frac{6}{7}.x=\frac{18}{23}\)
b) \(2\frac{1}{2}.x=\frac{5}{6}\)
c) \(x:2\frac{3}{4}=9\frac{5}{8}\)
d)\(7\frac{1}{7}.\frac{1}{7}.x=22\frac{1}{8}\)
Tính giá trị của biểu thức, tính nhanh nếu có thể
9) \(\frac{13}{50}\) + 9% + \(\frac{41}{100}\) + 24%
10) 2011,2012 . 2000 ( \(\frac{5}{6}\) - \(\frac{1}{3}\) - 50% ) . 1,234 + 10
11) \(\frac{120-0,5.40.5.0,2.20.0,25-20}{1+5+9+........+33+37}\)
12) \(6\frac{2}{7}+7\frac{3}{5}+8\frac{6}{9}+9\frac{1}{4}+\frac{2}{5}+\frac{5}{7}+\frac{1}{3}+\frac{3}{4}+1997\)
Tìm x biết
a) x + \(2\frac{3}{4}=5\frac{2}{3}\)
b)X x \(3\frac{1}{2}=4\frac{3}{4}\)
c) x - \(4\frac{1}{5}=3\frac{2}{7}\)
d) x - \(\frac{3}{4}=6\text{x}\frac{3}{8}\)
e) \(\frac{7}{8}:x=3\frac{1}{2}\)
Tính hợp lí:
A = \(\left(\frac{-4}{5}+\frac{4}{3}\right)+\left(\frac{-5}{4}+\frac{14}{5}\right)-\frac{7}{3}\)
B= \(\frac{8}{3}.\frac{2}{5}.\frac{3}{8}.10.\frac{19}{92}\)
C= \(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{14}+1\frac{5}{7}\)
Bài 4: THực hiện phép tính một cách hợp lý:
a) \(\frac{7}{19}.\frac{8}{11}+\frac{3}{11}.\frac{7}{19}+\frac{-12}{19}\) b) \(\frac{-7}{25}.\frac{39}{-14}.\frac{50}{78}\) c) \(\left(\frac{3}{8}+\frac{-3}{4}+\frac{7}{12}\right):\frac{5}{6}+\frac{1}{2}\)
Bài 12 : Thực hiện phép tính một cách hợp lí:
p) \(\frac{-5}{9}+\frac{8}{15}+\frac{-2}{11}+\frac{4}{-9}+\frac{7}{15}\) q) \(\frac{5}{13}+\frac{-5}{17}+\frac{-20}{41}+\frac{8}{13}+\frac{-21}{41}\) r) \(\frac{1}{5}+\frac{-2}{9}+\frac{-7}{9}+\frac{4}{5}+\frac{16}{17}\)
