a)  20 : 2 2 − 5 9 : 5 8 = 5 − 5 = 0

b)  ( 5 19 : 5 17 − 4 ) : 7 0 = ( 5 2 − 4 ) : 1 = 21

c)  295 − ( 31 − 2 2 .5 ) 2 = 295 − 11 2 = 174

a 20:2^2 -5^9:5^8

= 20:4 - 5^1

=5-5

=0

a)  20 : 2 2 − 5 9 : 5 8 = 5 − 5 = 0.

b)  ( 5 19 : 5 17 − 4 ) : 7 0 = ( 5 2 − 4 ) : 1 = 21.

c)  295 − ( 31 − 2 2 .5 ) 2 = 295 − 11 2 = 174.

;)

Ta có: A = 1+(-2)+3+(-4)+....+2003+(-2004) = 2005

     => A = (-1)+(-1)+(-1)+....+(-1) = (-1) x 2004 = -2004

1428:{23-[(8.81-369):31]}

= 1428 : { 23 - [ 279 : 31 ] }

= 1428 : { 23 - 9 }

= 1428 : 14

= 102

1428:{23-[(8.81-369):31]}

=1428:{23-[(648-369):31]}

=1428:{23-[279:31]}

=1428:{23-9}

=1428:14

=102

Học tốt~

a) \(26+150+74=\left(26+74\right)+150=100+150=250\).

b) \(35.46+54.35=35.\left(46+54\right)=35.100=3500\).

c) \(\left(-31\right)+\left[20-\left(7-4\right)^2\right]=\left(-31\right)+20-3^2=\left[\left(-31\right)-9\right]+20=-40+20=-20\)

a, 28 . (-2).3 - { 136 + [54 - 28 : (69 - 71).2 ]}

=-168- { 136 + [54 - 28 : (-2).2 ]}

=-168 - [136 + (54+28)]

=-168 - 218

=-386

b) 203.46-203.37+203

=203.46-203.37+203.1

=203.(46-37+1)

=203.10

=2030

c)21+23+25+27+29-31-33-35-37-39

=(21-31)+(23-33)+(25-35)+(27-37)+(29-39)

= -10 + (-10) + (-10) + (-10) + (-10)

=-50

d) 18.17-3.6.17

=18.17-18.17

= 0

e,33. ( 107- 112) - 107 . ( 33- 112)

=33.107- 33.112- 107.33+107.112

=(33.107- 33.112- 107.33)+107.112

=33(107-112-107)+107.112

=-33.112+107.112

=112.(-33+107)

=112.74

=8288

CHÚC BẠN MAY MẮN

\(a)\)

\(\left(-31\right)+\left(50-19\right)-\left(150-31\right)\)

\(=\left(-31\right)+50-19-150+31\)

\(=\left(-150\right)-19\)

\(=-169\)

\(b)\)

\(25.\left(45-17\right)-45.\left(25-17\right)\)

\(=25.45-25.17-45.25+45.17\)

\(=0\)

\(c)\)

\(\frac{-1}{12}+\frac{4}{3}=\frac{5}{4}\)

\(d)\)

\(3+\frac{-5}{20}+\frac{30}{75}+\frac{-7}{4}\)

\(=\left(\frac{3}{5}+\frac{30}{75}\right)-\left(\frac{5}{20}+\frac{7}{4}\right)\)

\(=1-2\)

\(=-1\)

a) (-31)+(50-19)-(150-31)

= (-31)+50+(-19)-150+(-31)
= (-31)+50-150+(-19)-(-31)
= (-31)+(-100)+12
= -119
b) 25(45-17)-45(25-17)
= 25.45-25.17-45.25-45.17
= 25(45-45)-25(17-17)
= 0
c) -1/12 + 4/3
= -1/12 + 16/12
= 15/12
= 5/4
d) 3/5+(-5)/20+30/75+(-7)/4
= 45/75+30/75+(-5)/20+(-35)/20
= 1+(-2)
= -1