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A) 7/38 x 9/11 +7/38 x 4/11 -7/38 x 2/11
=7/38.(9/11+4/11-2/11)
=7/38
B) 5/31 x 21/25 + 5/31 x -7/10 - 5/31 x 9/20
=5/31.(21/25-7/10-9/20)
=5/31.(-31/100)
=-1/20
Bài làm
a) \(\left(\frac{3}{8}+\frac{-1}{4}+\frac{5}{12}\right):\frac{2}{3}\)
\(=\left(\frac{9}{24}+\frac{-6}{24}+\frac{10}{24}\right).\frac{3}{2}\)
\(=\frac{13}{24}.\frac{3}{2}\)
\(=\frac{39}{48}\)
b) \(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{11}+1\frac{5}{7}\)
\(=-\frac{5}{7}.\left(\frac{2}{11}+\frac{9}{11}\right)+\frac{12}{7}\)
\(=-\frac{5}{7}.1+\frac{12}{7}\)
\(=\frac{7}{7}\)
\(=1\)
c) \(0,25:\left(10,3-9,8\right)-\frac{3}{4}\)
\(=\frac{25}{100}:\left(0,5\right)-\frac{3}{4}\)
\(=\frac{5}{4}:\frac{1}{2}-\frac{3}{4}\)
\(=\frac{5}{4}.2-\frac{3}{4}\)
\(=\frac{5}{2}-\frac{3}{4}\)
\(=\frac{10}{4}-\frac{3}{4}=\frac{7}{4}\)
d) \(-\frac{5}{9}.\frac{13}{28}-\frac{13}{28}.\frac{4}{9}\)
\(=-\frac{13}{28}\left(\frac{5}{9}+\frac{4}{9}\right)\)
\(=-\frac{13}{28}.\frac{9}{9}\)
\(=-\frac{13}{28}.1\)
\(=-\frac{13}{28}\)
a, 1/2 x ( 2/9 + 3/7 - 5/27 )
= 1/2 x ( 41/63 - 5/27 )
= 1/2 x 88/189
= 44/189
b, (-5/8 + 1,75 + 8/35) : (-3 và 9/10)
= (-5/8 + 7/4 + 8/35) : (-39/10)
= (9/8 + 8/35) : (-39/10)
=379/280 : (-39/10)
= -379/1092
c, 1/3 x 5/7 - 5/27 x 36/14
= 5/21 - 10/21
= -5/21
Chúc bạn học tốt !
a) 1/2 x (\(\frac{42}{189}-\frac{81}{189}-\frac{35}{189}\))=1/2 x 88/189 = 44/189
b) ( \(\frac{-5}{8}+\frac{7}{4}+\frac{8}{35}\)) : \(-3\frac{9}{10}\)
= ( \(\frac{-175}{280}+\frac{490}{280}+\frac{64}{280}\)) : \(\frac{-39}{10}\)
=\(\frac{379}{280}\) x \(\frac{-10}{39}\)=\(\frac{-379}{1092}\)
c) \(\frac{5}{21}\)- \(\frac{10}{21}\)= \(\frac{-5}{21}\)
a) 5/9 + 4/9 . 3/7 + 4/9 . 4/7
= 5/9 + 4/9 . (3/7 + 4/7)
= 5/9 + 4/9 . 1
= 5/9 + 4/9
= 1
a,30-7-8+9-11
=(30-7-8-11)+9=4+9=13
b,40-2+(-40)-2+4
=(40-40)+(4-2-2)=0
c,15-2+(-7)-9+(-11)
=15-(2+7+9+11)=15-29=-14
d,28-1+35-36-27
=(28-27)(+(35-36)-1=1-1-1=-3
có j ko hiểu thì add fr mình nha :)))