9×10-29+31=?
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1) $(-35)\cdot18+28\cdot35$
$=35\cdot(-18)+28\cdot35$
$=35\cdot(-18+28)$
$=35\cdot10$
$=350$
2) $53\cdot29-47\cdot(-29)$
$=53\cdot29-47\cdot(-1)\cdot29$
$=53\cdot29+47\cdot29$
$=29\cdot(53+47)$
$=29\cdot100$
$=2900$
3) $125\cdot(-24)+24\cdot225$
$=(-125)\cdot24+24\cdot225$
$=24\cdot(-125+225)$
$=24\cdot100$
$=2400$
4) $26\cdot(-121)-121\cdot(-36)$
$=-121\cdot[26+(-36)]$
$=-121\cdot(26-36)$
$=-121\cdot(-10)$
$=121\cdot10$
$=1210$
5) $65\cdot(-25)+25\cdot(-23)$
$=-65\cdot25+25\cdot(-23)$
$=25\cdot(-65-23)$
$=25\cdot(-88)$
$=-2200$
6) $237\cdot(-26)+26\cdot137$
$=-237\cdot26+26\cdot137$
$=26\cdot(-237+137)$
$=26\cdot(-100)$
$=-2600$
7) $30\cdot(-125)+25\cdot30$
$=30\cdot(-125+25)$
$=30\cdot(-100)$
$=-3000$
8) $(-37)\cdot69+(-31)\cdot37$
$=37\cdot(-69)+37\cdot(-31)$
$=37\cdot(-69-31)$
$=37\cdot(-100)$
$=-3700$
9) $31\cdot72-31\cdot70-31\cdot2$
$=31\cdot(72-70-2)$
$=31\cdot(2-2)$
$=31\cdot0$
$=0$
10) $(-12)\cdot47+(-12)\cdot52+(-12)$
$=-12\cdot(47+52+1)$
$=-12\cdot100$
$=-1200$
$\text{#}Toru$
a: \(5\cdot11\cdot18+9\cdot31\cdot10+4\cdot29\cdot45\)
\(=11\cdot\left(5\cdot18\right)+31\cdot\left(9\cdot10\right)+29\cdot2\cdot\left(2\cdot45\right)\)
\(=90\left(11+31+29\cdot2\right)\)
\(=90\cdot100=9000\)
b: \(37\cdot39+78\cdot14+13\cdot85+52\cdot55\)
\(=37\cdot39+39\cdot2\cdot14+13\cdot85+13\cdot4\cdot55\)
\(=39\left(37+2\cdot14\right)+13\cdot\left(85+4\cdot55\right)\)
\(=39\cdot65+13\cdot305\)
\(=13\left(65\cdot3+305\right)=13\cdot500=6500\)
a)
5.11.18+9.31.10+4.29.455.11.18+9.31.10+4.29.45
=90.11+90.31+2.29.90=90.11+90.31+2.29.90
=90.(11+31+2.29)=90.(11+31+2.29)
=90.100=9000
b)
37.39+78.14+13.85+52.5537.39+78.14+13.85+52.55
=37.39+39.2.14+13.5.17+13.4.5.11=37.39+39.2.14+13.5.17+13.4.5.11
=39.(37+2.14)+65.17+65.44=39.(37+2.14)+65.17+65.44
=39.65+65.(17+44)=39.65+65.(17+44)
=39.65+65.61=39.65+65.61
=65.(39+61)=65.(39+61)
=65.100=6500
\(\frac{9}{8}-\frac{-11}{8}=\frac{9-\left(-11\right)}{8}=\frac{9+11}{8}=\frac{20}{8}=\frac{5}{2}\)
\(-\frac{1}{2}-\frac{5}{2}=\frac{-1-5}{2}=\frac{-6}{2}=-3\)
\(\frac{4}{3}-\frac{7}{3}=\frac{4-7}{3}=\frac{11}{3}\)
\(\frac{3}{-5}-\frac{-8}{10}=\frac{6}{-10}-\frac{-8}{10}=\frac{-6}{10}-\frac{-8}{10}=\frac{-6-\left(-8\right)}{10}=\frac{-6+8}{10}=\frac{2}{10}=\frac{1}{5}\)
\(\frac{5}{7}-\frac{-3}{21}=\frac{5}{7}-\frac{-1}{7}=\frac{5-\left(-1\right)}{7}=\frac{5+1}{7}=\frac{6}{7}\)
\(\frac{4}{-3}-\frac{9}{27}=\frac{4}{-3}-\frac{1}{3}=\frac{-4}{3}-\frac{1}{3}=\frac{-4-1}{3}=\frac{-5}{3}\)
\(\frac{7}{29}-\frac{9}{29}=\frac{7-9}{29}=\frac{2}{29}\)
\(\frac{-7}{22}-\frac{9}{22}=\frac{-7-9}{22}=\frac{-16}{22}=\frac{-8}{11}\)
\(\frac{-23}{7}-\frac{31}{7}=\frac{-23-31}{7}=\frac{-54}{7}\)
a) \(24\left(16-5\right)-16\left(24-5\right)\)
\(=24.16-24.5-16.24+16.5\)
\(=\left(24.16-16.24\right)-24.5+16.5\)
\(=5\left(-24+16\right)\)
\(=5\left(-8\right)\)
\(=-40\)
b) \(29\left(9-13\right)-19\left(29-13\right)\)
\(=29.9-29.13-19.29+19.13\)
\(=\left(29.9-19.29\right)-\left(29.13-19.13\right)\)
\(=29\left(9-19\right)-13\left(29-19\right)\)
= \(29.\left(-10\right)-13.10\)
\(=-290-130\)
\(=-420\)
c) \(31.\left(-18\right)+31.\left(-81\right)-31\)
\(=31\left[-18+\left(-81\right)\right]-31\)
\(=31.\left(-99\right)-31\)
\(=31\left(-99-1\right)\)
\(=31.\left(-100\right)\)
\(=-3100\)
d) \(-12.47+\left(-12\right).52+\left(-12\right)\)
\(=-12\left(47+52+1\right)\)
\(=-12.100\)
\(=-1200\)
e) \(\left(-6-2\right)\left(-6+2\right)\)
= \(-8.\left(-4\right)\)
\(=32\)
\(f\)) \(\left(-5+9\right)\left(-4\right)\)
\(=4.\left(-4\right)\)
\(=-16\)
a) \(39\times118+29\times82\)
\(=39\times2\times59+29\times2\times41\)
\(=2\times\left(39\times59+29\times41\right)\)
\(=2\times\left(2301+1189\right)\)
\(=2\times3490\)
\(=6980\)
b) \(37\times39+78\times14-13\times85-52\times55\)
\(=37\times3\times13+6\times13\times14+13\times85-4\times13\times55\)
\(=13\times\left(37\times3+6\times14+85-4\times55\right)\)
\(=13\times\left(111+84+85-220\right)\)
\(=13\times\left(280-220\right)\)
\(=13\times60\)
\(=780\)
c) \(368:16+752:16+480:16\)
\(=\left(368+752+480\right):16\)
\(=\left(1120+480\right):16\)
\(=1600:16\)
\(=100\)
d) \(5\times11\times18+9\times31\times10+4\times29\times45\)
\(=5\times11\times9\times2+9\times31\times10+2\times2\times29\times5\times9\)
\(=10\times9\times11+10\times9\times31+10\times29\times2\times9\)
\(=90\times11+90\times31+90\times29\times2\)
\(=90\times\left(11+31+29\times2\right)\)
\(=90\times\left(42+58\right)\)
\(=90\times100\)
\(=9000\)
D=5/3.5+5/5.7+5/7.9+5/9.11+...+5/27.29+5/29.31
2D=10/3.5+10/5.7+10/7.9+10/9.11+...+10/27.29+10/29.31
2D=5/3-5/5+5/5-5/7+5/7-5/9+5/9-5/11+...+5/27-5/29+5/29-5/31
2D=5/3-5/31
2D=155/93-15/93
2D=140/93
D=140/93:2
D=70/93
a/\(\frac{1212}{1313}=\frac{12x101}{13x101}=\frac{12}{13}\)
Vậy \(\frac{12}{13}=\frac{1212}{1313}\)
b/Ta có:
\(\frac{4}{5}< 1\)
\(\frac{10}{9}>1\)
=>\(\frac{4}{5}< 1< \frac{10}{9}\Rightarrow\frac{4}{5}< \frac{10}{9}\)
c/\(\frac{17}{15}=1+\frac{2}{15}\)
\(\frac{31}{29}=1+\frac{2}{29}\)
Vì \(\frac{2}{15}>\frac{2}{29}\) nên \(\frac{17}{15}>\frac{31}{29}\)
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chú ý: dấu "=>" có nghĩa là "suy ra"
5, 31+1240++1829=3100
6. -19+836+1829=2646
7. 54.43-32.35=2322-1120=1202
8 2018(31+16+50)=2018.97=195746
9. 16(34-21+55)=16.68=1088
10. 63(29-31-98)=63.(-100)=-6300
a) \(\dfrac{25}{37}\times\dfrac{18}{29}+\dfrac{18}{29}\times\dfrac{12}{37}\)
\(=\dfrac{18}{29}\times\left(\dfrac{25}{37}+\dfrac{12}{37}\right)\)
\(=\dfrac{18}{29}\times\dfrac{37}{37}\)
\(=\dfrac{18}{29}\times1\)
\(=\dfrac{18}{29}\)
b) \(\dfrac{31}{85}\times\dfrac{11}{19}+\dfrac{31}{85}\times\dfrac{12}{19}-\dfrac{42}{19}\times\dfrac{31}{85}\)
\(=\dfrac{31}{85}\times\left(\dfrac{11}{19}+\dfrac{12}{19}-\dfrac{42}{19}\right)\)
\(=\dfrac{31}{85}\times\dfrac{-19}{19}\)
\(=\dfrac{31}{85}\times-1\)
\(=-\dfrac{31}{85}\)
c) \(\dfrac{16}{53}:\dfrac{17}{9}-\dfrac{16}{53}:\dfrac{17}{8}\)
\(=\dfrac{16}{53}:\left(\dfrac{9}{17}-\dfrac{8}{17}\right)\)
\(=\dfrac{16}{53}:\dfrac{1}{17}\)
\(=\dfrac{16}{901}\)
c) \(\dfrac{1}{5}\times\dfrac{12}{31}\times\dfrac{4}{3}+\dfrac{19}{31}\times\dfrac{4}{15}\)
\(=\dfrac{4}{15}\times\dfrac{12}{31}+\dfrac{19}{31}\times\dfrac{4}{15}\)
\(=\dfrac{4}{15}\times\left(\dfrac{12}{31}+\dfrac{19}{31}\right)\)
\(=\dfrac{4}{15}\times\dfrac{31}{31}\)
\(=\dfrac{4}{15}\times1\)
\(=\dfrac{4}{15}\)
a: =18/29*(25/37+12/37)
=18/29
b: =31/85(11/19+12/19-42/19)
=-31/85
c; =16/53(9/17+8/17)=16/53
d: =4/15(12/31+19/31)=4/15
9×10-29+31
= 90 - 29 + 31
= 61 + 31
= 92
~HT~
9*10-29+31
=90-60
=30