Tính
( 21 + 19 )4 : 402 + 31 –1600
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A) =(5+(-15))+(9+(-19))+(-11)+(13+17)+(21+(-23))
=(-10)+(-10)+(-11)+20+(-2)
=((-10)+(-10))+(-11)+(-2)+20
=(-20)+(-11)+20+(-2)
=((-20)+20)+((-11)+(-2))
=0+(-13)=-13
B) doi ti !!!!! Tich cho mik nha
1) \(35.18-5.7.28=35.18-35.28=35\left(18-28\right)=-350\)
2) \(45-5\left(12+9\right)=45-60-45=-60\)
3) \(24\left(16-5\right)-16\left(24-5\right)=24.16-24.5-16.24+16.5=5\left(16-24\right)=5.8=40\)
4) \(29\left(19-13\right)-19\left(29-13\right)=29.19-29.13-19.29+19.13=13\left(19-29\right)=-130\)
5) \(31.\left(-18\right)+31.\left(-81\right)-31=-31.\left(18+81+1\right)=-3100\)
6) \(\left(-12\right).47+\left(-12\right).52+\left(-12\right)=\left(-12\right)\left(47+52+1\right)=-1200\)
7) \(13\left(23+22\right)-3\left(17+28\right)=13.45-3.45=45.\left(13-3\right)=450\)
8) \(-48+48.\left(-78\right)+48.\left(-21\right)=-48\left(1+78+21\right)=-4800\)
1) 35.18 - 5.7.28
= 35.18 - 35.28
= 35.(18 - 28)
= 35.(-10)
= -350
2) 45 - 5.(12 + 9)
= 45 - 5.12 - 5.9
= 45 - 60 - 45
= (45 - 45) - 60
= 0 - 60
= -60
3) 24.(16 - 5) - 16.(24 - 5)
= 24.16 - 24.5 - 16.24 + 16.5
= (24.16 - 16.24) - (24.5 + 16.5)
= 0 - (24.5 + 16.5)
= -24.5 + 16.5
= 5.(-24 + 16)
= 5.(-8)
= -40
4) 29.(19 - 13) - 19.(29 - 13)
= 29.19 - 29.13 - 19.29 + 19.13
= (29.19 - 19.29) + (19.13 - 29.13)
= 0 + (19.13 - 29.13)
= 19.13 - 29.13
= 13.(19 - 29)
= 13.(-10)
= -130
5) 31.(-18) + 31.(-81) - 31
= 31.(-18 - 81 - 1)
= 31.(-100)
= -3100
6) (-12).47 + (-12).52 + (-12)
= (-12).(47 + 52 + 1)
= (-12).100
= -1200
7) 13.(23 + 22) - 3.(17 + 28)
= 13.45 - 3.45
= 45.(13 - 3)
= 45.10
= 450
8) -48 + 48.(-78) + 48.(-21)
= 48.(-1) + 48.(-78) + 48.(-21)
= 48.(-1 - 78 - 21)
= 48.(-100)
= -4800
Cố gắng lên nhé em Hoàng Mai Hoa
1)35.18-5.7.28
= 35 . 18 - 35 . 28
= 35 . ( 18 - 28 )
= 35 . ( - 10 )
= - 350
\(=\dfrac{17}{31}\left(-\dfrac{5}{19}-\dfrac{4}{19}\right)=\dfrac{17}{31}.\dfrac{-9}{19}=-\dfrac{153}{589}\)
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
(21 + 19)4 : 402 + 31 - 1600
= 404 : 402 - 402 + 31
= 402 - 402 + 31
= 31