348,39 + 402,5=750,89

700,64 - 455,37=245,27

23,48 + 6,35 - 10,3=19,53

k nha

750.89

245.27

19.53

245,27

Đáp án B

29.83

=29.83

=29.83

tui chỉ làm phần b thôi há !

B=\(\frac{3}{4}\)+\(\frac{27}{28}\)+\(\frac{69}{70}\)+...+\(\frac{867}{868}\)=\(\frac{4-1}{4}\)+\(\frac{28-1}{28}\)+\(\frac{70-1}{70}\)+...+\(\frac{868-1}{868}\)

= 1+1+..+1 -(\(\frac{1}{4}\)+\(\frac{1}{28}\)+\(\frac{1}{70}\)+...+\(\frac{1}{868}\)) = 10 - \(\frac{1}{3}\)(\(\frac{3}{1.4}\)+\(\frac{3}{4.7}\)+\(\frac{3}{7.10}\)+...+\(\frac{3}{28.31}\))

=10-\(\frac{1}{3}\)(1-\(\frac{1}{4}\)+\(\frac{1}{4}\)-\(\frac{1}{7}\)+\(\frac{1}{7}\)-\(\frac{1}{10}\)+...+\(\frac{1}{28}\)-\(\frac{1}{30}\))=10-\(\frac{1}{3}\)(1-\(\frac{1}{30}\))=10-\(\frac{1}{3}\).\(\frac{29}{30}\)=10-\(\frac{29}{30}\)=\(\frac{271}{30}\)

T=147,35-23,48-36,12-47,35+23,48+136,12

T=(147;35-47,35)+(23,48-23,48)+(136,12-36,12)

T=100+0+100

T=200

b, 2,4 x 4,567 + 5, 433 x 2,4 

 = 2,4 x ( 4,567 + 5,433)

 = 2,4 x 1 0

 = 24

d, 20,14 x 99 + 20,14

 = 20,14 x( 99 + 1)

  = 20,14 x 100

  = 2014

à thế thay số 5 bằng số 8 hộ mình nha

Đúng cho mình đi

Bài 1: 

a: =25+75=100

b: =60-17-43+12=12

c: =-2-18=-20

d: =-3+36-17=36-20=16

Bài 2: 

a: =-102

b: =-1000

c: =12x15=180

d: =21x(-10)=-210

B1

a 100

b 12

c -20

d 16

B2

a -102

b -1000

c 180

d -210

Bài 1:Tính

 a)(-12)+25+75+12 = 100

b)60+12+(-17)+(-43)=12
c)(-2)+(-87)+(-18)+87=-20
d)(-1)+(-2)+36+(-17)=16
Bài 2:Tính
b)8 . (-125)=-100
c)(-12) . (-15)=180
d)21 . (- 3)+(- 21 ) . 7=-210

\(39,52-23,48+20,48-56,52\)

\(=\left(39,52-26,52\right)-\left(23,48-20,48\right)\)

\(=3-3\)

\(=0\)

\(39,52-23,48+20,48-26,52\\ =\left(39,52-26,52\right)+\left(-23,48+20,48\right)\\ =13-3\\ =10.\)

Mình cảm ơn

lỗi ảnh , up lại câu  hỏi

lỗi

Lỗi bạn nhé :)