a) = 1/2 + 1/3 = 5/6
b) = 2/5 + 2/3 = 16/15
c) = 7/11 . ( 3/4 + 1/4 ) + 4/11
= 7/11 . 1 + 4/11
= 7/11 + 4/11
= 1
d) = ( 3/4 + 1/2 + 1/4 ) . 8/3
= 3/2 . 8/3
= 4
\(e.\dfrac{7}{10}\cdot\dfrac{-3}{5}+\dfrac{7}{10}\cdot\dfrac{-2}{5}-\dfrac{3}{10}\)
\(=\dfrac{7}{10}\cdot\left[\left(\dfrac{-3}{5}\right)+\left(\dfrac{-2}{5}\right)\right]-\dfrac{3}{10}\)
\(=\dfrac{7}{10}\cdot1-\dfrac{3}{10}=\dfrac{4}{10}=\dfrac{2}{5}\)
\(f.\dfrac{-3}{7}\cdot\dfrac{5}{9}+\dfrac{4}{9}\cdot\dfrac{-3}{7}+2\dfrac{3}{7}\)
\(=\dfrac{-3}{7}\cdot\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\dfrac{17}{3}\)
\(=\dfrac{-3}{7}\cdot1+\dfrac{17}{3}=\dfrac{-9}{21}+\dfrac{119}{21}=\dfrac{110}{21}\)
\(g.\dfrac{5}{9}\cdot\dfrac{10}{17}+\dfrac{5}{9}\cdot\dfrac{9}{17}-\dfrac{5}{9}\cdot\dfrac{2}{17}\)
\(=\dfrac{5}{9}\cdot\left(\dfrac{10}{17}+\dfrac{9}{17}-\dfrac{2}{17}\right)\)
\(=\dfrac{5}{9}\cdot1=\dfrac{5}{9}\)
1. \(A=\dfrac{2\left(\dfrac{1}{5}+\dfrac{1}{7}-\dfrac{1}{9}-\dfrac{1}{11}\right)}{4\left(\dfrac{1}{5}+\dfrac{1}{7}-\dfrac{1}{9}-\dfrac{1}{11}\right)}=\dfrac{2}{4}=\dfrac{1}{2}\)
2. \(B=\dfrac{1^2.2^2.3^2.4^2}{1.2^2.3^2.4^2.5}=\dfrac{1}{5}\)
3.\(C=\dfrac{2^2.3^2.\text{4^2.5^2}.5^2}{1.2^2.3^2.4^2.5.6^2}=\dfrac{125}{36}\)
4.D=\(D=\left(\dfrac{4}{5}-\dfrac{1}{6}\right).\dfrac{4}{9}.\dfrac{1}{16}=\dfrac{19}{30}.\dfrac{1}{36}=\dfrac{19}{1080}\)
A,
\(\left(7\dfrac{4}{9}+3\dfrac{7}{11}\right)-3\dfrac{4}{9}=7\dfrac{4}{9}+3\dfrac{7}{11}-3\dfrac{4}{9}\)
\(=7\dfrac{4}{9}-3\dfrac{4}{9}+3\dfrac{7}{11}=4+3\dfrac{7}{11}=7\dfrac{7}{11}\)
B,
\(5\dfrac{2}{7}.\dfrac{8}{11}+5\dfrac{2}{7}.\dfrac{5}{11}-5\dfrac{2}{7}.\dfrac{2}{11}=5\dfrac{2}{7}.\left(\dfrac{8}{11}+\dfrac{5}{11}-\dfrac{2}{11}\right)\)
\(=5\dfrac{2}{7}.1=5\dfrac{2}{7}\)
\(\dfrac{-5}{9}+1\dfrac{5}{9}.\left(\dfrac{3}{4}-\dfrac{2}{5}\right):7^2\\ =\dfrac{-5}{9}+\dfrac{14}{9}.\left(\dfrac{3}{4}-\dfrac{2}{5}\right):49\\ =\dfrac{-5}{9}+\dfrac{14}{9}.\left(\dfrac{15}{20}-\dfrac{8}{20}\right):49\\ =\dfrac{-5}{9}+\dfrac{14}{9}.\dfrac{7}{20}:49\\ =\dfrac{-5}{9}+\dfrac{49}{90}:49\\ =\dfrac{-5}{9}+\dfrac{1}{90}\\ =\dfrac{-50}{90}+\dfrac{1}{90}\\ =\dfrac{-49}{90}\)
\(1\dfrac{13}{15}.0,75-\left(\dfrac{104}{195}+25\%\right).\dfrac{24}{47}-3\dfrac{12}{13}:3\\ =\dfrac{28}{15}.\dfrac{3}{4}-\left(\dfrac{8}{15}+\dfrac{1}{4}\right).\dfrac{24}{47}-\dfrac{51}{13}:3\\ =\dfrac{7}{5}-\left(\dfrac{32}{60}+\dfrac{15}{60}\right).\dfrac{24}{47}-\dfrac{51}{13}.\dfrac{1}{3}\\ =\dfrac{7}{5}-\dfrac{47}{60}.\dfrac{24}{47}-\dfrac{17}{13}\\ =\dfrac{7}{5}-\dfrac{2}{5}-\dfrac{17}{13}\\ =1-\dfrac{17}{13}\\ =\dfrac{13}{13}-\dfrac{17}{13}\\ =\dfrac{-4}{13}\)
a: =3/4-5/4+3/2x12/5=-1/2+36/10=-5/10+36/10=31/10
b: \(=\dfrac{-7}{13}\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\dfrac{7}{13}+8=8\)
a: \(=\left(\dfrac{3}{17}+\dfrac{14}{17}\right)+\left(\dfrac{-5}{13}-\dfrac{8}{13}\right)+\left(\dfrac{-18}{35}-\dfrac{17}{35}\right)\)
=1-1-1
=-1
b: \(=\dfrac{-3}{8}\left(\dfrac{1}{6}+\dfrac{5}{6}\right)+\dfrac{-5}{8}=\dfrac{-3}{8}-\dfrac{5}{8}=-1\)
c: \(=\dfrac{4}{4}\cdot\dfrac{5}{15}\cdot\dfrac{11}{11}=\dfrac{1}{3}\)
a)\(=\left(-\dfrac{5}{13}+\dfrac{-8}{13}\right)+\left(-\dfrac{18}{35}-\dfrac{17}{35}\right)+\left(\dfrac{3}{14}+\dfrac{14}{17}\right)=-1-1+1=-1\)
b)\(=\dfrac{-3}{8}.\left(\dfrac{1}{6}+\dfrac{5}{6}\right)-\dfrac{10}{16}=-\dfrac{3}{8}.1-\dfrac{10}{16}=-\dfrac{6}{16}-\dfrac{10}{16}=-\dfrac{16}{16}=-1\)
c)\(\dfrac{-4.5.11}{11.5.3.-4}=\dfrac{1}{3}\)
Bài 1:
\(a,=\frac{2}{3}-\frac{16}{3}=\frac{-14}{3}\)
\(b,=\left(\frac{3}{7}+\frac{4}{7}\right)+\left(-\frac{6}{19}+\frac{-13}{19}\right)=1-1=0\)
\(c,=\frac{3}{5}.\left(\frac{8}{9}-\frac{7}{9}+\frac{26}{9}\right)=\frac{3}{5}.3=\frac{9}{5}\)
a,\(\dfrac{1}{2}\).\(\dfrac{4}{3}\)-\(\dfrac{20}{3}\).\(\dfrac{4}{5}\)=\(\dfrac{2}{3}\)-\(\dfrac{16}{3}\)=-\(\dfrac{14}{3}\)
a
2/3 - 16/3= -14/3
(3/4+4/7)+[(-6/19)+(-13/19)= 1+ (-1)=0
a)
a) 2/3 - 16/3 = -14/3
a=-14/3
B=0
C=9/5
a,2/3-16/3=-14/3
b,(3/7+4/7)+(-6/19+-13/19)=1+(-1)=0
c,3/5.(8/9-7/9+26/9)=3/5.3=9/5
) \dfrac{1}{2} \cdot \dfrac{4}{3}-\dfrac{20}{3} \cdot \dfrac{4}{5}21⋅34−320⋅54
=\dfrac{2}{3}-\dfrac{16}{3}=32−316
=-\dfrac{14}{3}=−314 ;
b) \dfrac{3}{7}+\dfrac{-6}{19}+\dfrac{4}{7}+\dfrac{-13}{19}73+19−6+74+19−13
=\left( \dfrac{3}{7}+\dfrac{4}{7} \right)+\left( \dfrac{-6}{19}+\dfrac{-13}{19} \right)=(73+74)+(19−6+19−13)
=\dfrac{7}{7}+\dfrac{-19}{19}=7
Đúng(0)
a)\(\dfrac{2}{3}-\dfrac{16}{3}=\dfrac{-14}{3}\).
b)\(\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\left(\dfrac{-6}{19}+\dfrac{-13}{19}\right)=1+\left(-1\right)=0\)
c)\(\dfrac{3}{5}.\left(\dfrac{8}{9}-\dfrac{7}{9}+\dfrac{26}{9}\right)=\dfrac{3}{5}.3=\dfrac{9}{5}\)
a) \dfrac{1}{2} \cdot \dfrac{4}{3}-\dfrac{20}{3} \cdot \dfrac{4}{5}21⋅34−320⋅
4
=\dfrac{2}{3}-\dfrac{16}{32
316−314
A,=2/3-16/3
=-14/3
B,
a) \dfrac{1}{2} \cdot \dfrac{4}{3}-\dfrac{20}{3} \cdot \dfrac{4}{5}21⋅34−320⋅54
=\dfrac{2}{3}-\dfrac{16}{3}=32−316
=-\dfrac{14}{3}=−314 ;
b) \dfrac{3}{7}+\dfrac{-6}{19}+\dfrac{4}{7}+\dfrac{-13}{19}73+19−6+74+19−13
=\left( \dfrac{3}{7}+\dfrac{4}{7} \right)+\left( \dfrac{-6}{19}+\dfrac{-13}{19} \right)=(73+74)+(19−6+19−13)
=\dfrac{7}{7}+\dfrac{-19}{19}=
Bài 1. (3 điểm) Thực hiện phép tính.
a) \dfrac{1}{2} \cdot \dfrac{4}{3}-\dfrac{20}{3} \cdot \dfrac{4}{5}21⋅34−320⋅54 ;
b) \dfrac{3}{7}+\dfrac{-6}{19}+\dfrac{4}{7}+\dfrac{-13}{19}73+19−6+74+19−13 ;
c) \dfrac{3}{5} \cdot \dfrac{8}{9}-\dfrac{7}{9} \cdot \dfrac{3}{5}+\dfrac{3}{5} \cdot \dfrac{26}{9}53⋅98−97⋅53+53⋅926.
Hướng dẫn giải:
a) \dfrac{1}{2} \cdot \dfrac{4}{3}-\dfrac{20}{3} \cdot \dfrac{4}{5}21⋅34−320⋅54
=\dfrac{2}{3}-\dfrac{16}{3}=32−316
=-\dfrac{14}{3}=−314 ;
b) \dfrac{3}{7}+\dfrac{-6}{19}+\dfrac{4}{7}+\dfrac{-13}{19}73+19−6+74+19−13
=\left( \dfrac{3}{7}+\dfrac{4}{7} \right)+\left( \dfrac{-6}{19}+\dfrac{-13}{19} \right)=(73+74)+(19−6+19−13)
=\dfrac{7}{7}+\dfrac{-19}{19}=77+19−19
=1+\left( -1 \right)=0=1+(−1)=0 ;
c) \dfrac{3}{5} \cdot \dfrac{8}{9}-\dfrac{7}{9} \cdot \dfrac{3}{5}+\dfrac{3}{5} \cdot \dfrac{26}{9}53⋅98−97⋅53+53⋅926
=\dfrac{3}{5} \cdot \left( \dfrac{8}{9}-\dfrac{7}{9}+\dfrac{26}{9} \right)=53⋅(98−97+926)
=\dfrac{3}{5} \cdot \dfrac{27}{9}=53⋅927
=\dfrac{3}{5} \cdot 3=53⋅3
=\dfrac{9}{5}=59.
a) \dfrac{1}{2} \cdot \dfrac{4}{3}-\dfrac{20}{3} \cdot \dfrac{4}{5}21⋅34−320⋅54
=\dfrac{2}{3}-\dfrac{16}{3}=32−316
=-\dfrac{14}{3}=−314 ;
b) \dfrac{3}{7}+\dfrac{-6}{19}+\dfrac{4}{7}+\dfrac{-13}{19}73+19−6+74+19−13
=\left( \dfrac{3}{7}+\dfrac{4}{7} \right)+\left( \dfrac{-6}{19}+\dfrac{-13}{19} \right)=(73+74)+(19−6+19−13)
=\dfrac{7}{7}+\dfrac{-19}{19}=
A) -14/3 b) 0 c) 9/5
a)1/2.4/3-20/3.4/5
=2/3-16/3
=-14/3
b)3/7+-6/19+4/7+-13/19
=(3/7+4/7)+(-6/19+-13/19)
=1+(-1)
=0
c)3/5.8/9-7/9.3/5+3/5.26/9
=3/5.(8/9-7/9+26/9)
=3/5.3
=9/5