a,

ssh:(2017-2)/5+1=404

tổng:(2017+2)*404/2=407838

b,

8*9*14+6*7*12+19*4*18=2*2*2*2*7+2*3*2*2*3+19*2*2*9*2=8(2*7+3*3+19*9)=8*194=1552

a)29 . (19 – 13) – 19 . (29 – 13)

= 29 . 6 – 19 . 16

= 174 – 304

= –130.

b)31.(-18)+31.(-81)-31       

= 31. [-18 + (-81) - 1 ]

= 31. (-100)

= -3100

c)(7.3-3):(-6)  

(7.3-3):(-6)

= (21-3):(-6)

= 18 : (-6)

= 3

d)72:[(-6).2+4)]       

= 72 : ( -12 + 4 )

= 72 : -8

= -9

Bài 2:

a)(-12).47+(-12).52+(-12)       

= (-12).(47+52+1)

= -1200

b)13.(23+22)-3.(17+28)  

13 . (23 + 22) - 3 . (17 + 28)

= 13 . 45 - 3 . 45

= ( 13 - 3 ) . 45

= 10 . 45

= 450

c)18-10:(-2)-7   

= 18-5+7

= 13+7

= 20

d)99:[(-7).2+5)

1. Tính nhanh

a) 29 . (19 – 13) – 19 . (29 – 13)

= 29 . 6 – 19 . 16

= 174 – 304

= –130.

b) 31 . (-18) + 31 . (-81) - 31       

= 31. [-18 + (-81) - 1 ]

= 31. (-100)

= -3100

c) (7 . 3 - 3) : (-6)

= (21 - 3) : (-6)

= 18 : (-6)

= 3

d) 72 : [(-6) . 2 + 4)]       

= 72 : ( -12 + 4 )

= 72 : -8

= -9

2. Tính nhanh

a) (-12) . 47 + (-12) . 52 + (-12)

= (-12) . (47 + 52 + 1)

= (-12) . 100

= -1200        
b) 13 . (23 + 22) - 3 . (17 + 28)   

= 13 . 45 - 3 . 45

= (13 - 3) . 45

= 10 . 45

= 450
c) 18 - 10 : (-2) - 7   

= 18-5+7

= 13+7

= 20

d) 99 : [(-7) . 2 + 5]

= 99 : -9

= -11

a,(-17)+(-83)+2017+53

= -100+2017+53

=1917+53

=1970

b,(-64)+(-12)+(-36)

= -76+(-36)

=-112

c,27.152-22.27+73.130

= 27.(152-22)+73.130

=27.130+73.130

=130.(27+73)

=130.100

=13000

A)  (-17)+ (-83)+ 2017+53

=(-17)+ 2017+(-83)+53

=2000+ 30

=2030

B)  (-64)+(-12)+(-36)

= -76+(-36)

=-103

C)  27. 152- 22. 27+ 73. 130

=27.(152-22+73). 130

=27. 203. 130

= 5481. 130

= 712530

a)(-17)+(-83)+2017+53

=[(-17)+(-83)]+[2017+53]

=(-100)+2070

=1970

b)Tương tự

c)27.152-22.27+73.130

=27.(152-22)+73.130

=27.130+73.130

=130.(27+73)

=130.100

=13000

Chúc bn học tốt

A = 2/7 + 11/7 -3/8 - 5/8 + 1/3 + 1/5 = 13/11 - 1 + 8/15

A = 2/11 + 8/15 = 118/125

B = - 3/17 + 3/17 + 2/13 = 2/13

C = - 3/8 - 5/8 + 12/15 = 1 - 12/15

C = - 1/5 

a) 500                  

b) 2303                

c) 537 

d) 35000

a) (-2017)- (28- 2017)

= -2017 -28 +2017

= (-2017 +2017) -28

= 0 -28

= -28

b) (17-299) +(17-26+299)

=17 -229 +17 -25 +229

=(17 +17) -(229 +229) -25

=34 -0 -25

=9

c) - (269 -357) + (269 -357)

=-269 +357 +269 -357

=(-269 +269) +(357 -357)

= 0 +0 =0

d) (123 +345)  + (456 -1230 - (2017 - (-345)))

=123 +345 +456 -1230 -2017 -345

=(345 -345) + (123 -1230) + (456 -2017)

=0 + (-1107) + (--1561)

= -2668

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

a,700

b,62

c,9297

d,95

e,13

f,-3

g,100

h,-160

i,3028

\(A=\frac{2}{7}+\left(-\frac{3}{8}\right)+\frac{11}{7}+\frac{1}{3}+\frac{1}{7}+\left(-\frac{5}{8}\right)\)

\(=\left(\frac{2}{7}+\frac{11}{7}+\frac{1}{7}\right)+\left(-\frac{3}{8}-\frac{5}{8}\right)+\frac{1}{3}\)

\(=2-1+\frac{1}{3}\)

\(=1+\frac{1}{3}\)

\(=\frac{4}{3}\)

\(B=-\frac{3}{17}+\left(\frac{2}{3}+\frac{3}{17}\right)\)

\(=-\frac{3}{17}+\frac{2}{3}+\frac{3}{17}\)

\(=\left(-\frac{3}{17}+\frac{3}{17}\right)+\frac{2}{3}\)

\(=0+\frac{2}{3}\)

\(=\frac{2}{3}\)

\(C=\frac{3}{8}+\frac{12}{25}+\frac{5}{-8}+\frac{2}{-5}+\frac{13}{25}\)

\(=\left(\frac{3}{8}-\frac{5}{8}\right)+\left(\frac{12}{25}+\frac{13}{25}\right)-\frac{2}{5}\)

\(=-\frac{1}{4}+1-\frac{2}{3}\)

\(=\frac{1}{12}\)

Đ/s : 2/3 nha bn

k cho mình nhé binn2011