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a) 820 và 720
vì 8>7 nên 820>720
b) 420 và 1620
vì 4<16 nên 420<1620
c) 277= (33)7= 321
815=( 34)5=320
vì 21>20 nên 321>320 hay 277> 815
e) 521= 520 . 5
vì 520 . 5>520 . 4 nên 521> 4 . 520
Bài 1 :
a,820 > 720
b, 420 = 1610
c, 277 > 815
d , 554 > 381
e, 521 > 4 . 520
f, 220 > 7.217
a. \(2\cdot125\cdot\left(-5\right)\cdot8\)
\(=\left(2\cdot\left(-5\right)\right)\cdot\left(125\cdot8\right)\)
\(=-10\cdot1000\)
\(=-10000\)
b. \(56\cdot\left(-35\right)+156\cdot35\)
\(=-1960+5460\)
\(=3500\)
c. \(\frac{11}{15}+\frac{-9}{10}=\frac{22}{30}+\frac{-27}{30}=\frac{-5}{30}=\frac{-1}{6}\)
d. \(\frac{-4}{5}+\frac{2}{7}+\frac{3}{31}+\frac{5}{7}+\frac{-1}{5}\)
\(=\left(\frac{-4}{5}+\frac{-1}{5}\right)+\left(\frac{2}{7}+\frac{5}{7}\right)+\frac{3}{31}\)
\(=-1+1+\frac{3}{31}\)
\(=0+\frac{3}{31}\)
\(=\frac{3}{31}\)
a: \(=36:4+2\cdot25=9+50=59\)
b: \(=79\left(82+18\right)=79\cdot100=7900\)
c: \(=49-9-\left(4^2+2^2\right)\)
\(=40-16-4=40-20=20\)
d: \(=16+\left[400:\left(200-42-138\right)\right]\)
\(=16+400:20=16+20=36\)
\(a,\frac{5}{16}:0,125-\left(2\frac{1}{4}-0,6\right)\cdot\frac{10}{11}\)
\(=\frac{5}{16}:\frac{1}{8}-\left(\frac{9}{4}-\frac{3}{5}\right)\cdot\frac{10}{11}\)
\(=\frac{5}{2}-\frac{33}{20}\cdot\frac{10}{11}\)
\(=\frac{5}{2}-\frac{3}{2}\)
\(=1\)
\(\frac{5}{16}:0,125-\left(2\frac{1}{4}-0,6\right).\frac{10}{11}\)
\(\Rightarrow\frac{5}{16}:\frac{125}{1000}-\left(\frac{9}{4}-\frac{6}{10}\right).\frac{10}{11}\)
\(\Rightarrow\frac{5}{16}:\frac{1}{8}-\left(\frac{9}{4}-\frac{3}{5}\right).\frac{10}{11}\)
\(\Rightarrow\frac{5}{16}.\frac{8}{1}-\left(\frac{45}{20}-\frac{12}{20}\right).\frac{10}{11}\)
\(\Rightarrow\frac{5}{2}-\frac{33}{20}.\frac{10}{11}\)
\(\Rightarrow\frac{5}{2}-\frac{3.1}{2.1}\)
\(\Rightarrow\frac{5}{2}-\frac{3}{2}=\frac{2}{2}=1\)
a) 31 . 65 + 31 . 35 - 500
=31(65+35)-500
=31..100-500
=3100-500
=2600
a, 31.56+31.35-500
=31(65+35)-500
=3100-500
=2600