a: =35/17-18/17-9/5+4/5

=1-1=0

b: =-7/19(3/17+8/11-1)

=7/19*18/187=126/3553

c: =26/15-11/15-17/3-6/13

=1-6/13-17/3

=7/13-17/3=-200/39

lớp 1 mà cậu

4.24.5²-(3³.18+3³.12)

=4.24.25-[27.(18+12)]

=(4.25).24-[27.30]

=100.24-810

=2400-810

=1590

4.24.5^2-(3^3.18+3^3.12)

31.15.7^2.4-31.49.40

1+2+3+4+5+6+7+8+9+10

1+3+5+7+9+11+13+15+19

2+6+10+14+22+23+26+34

5+8+11+14+17+20+23+26+29

1+6+11+16+21+26+31+36+41+47+51

10+13+16+19+22+25+28+31+34+37+40

5+7+9+11+13+15+17+3+8+13+18+23+28

4+7+10+13+16+19+5+9+13+17+21+25 = 1590

#HT#

1+3+5+7+9+11+13+15+17+19=100

1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 = 100

k mình nha

bằng 100 tròn nha bạn 

1+3+5+7+9+11+13+15+17+19

=(1+19)+(3+17)+(5+15)+(7+13)+(9+11)

=20+20+20+20+20

=20x5

=100

19+1  +   17+3    +    15+5    +     13+7    +    11+9=20 nhan 5 =100. nhé

1+3+5+7+...+19= ( 1 +19) + (2+18) = (3+17) +....+ (9+11)

=20+20+20+20+20

=100

x= 100

\(x=1+3+5+7+9+11+13+15+17+19\)\(x=\left(1+19\right)+\left(3+17\right)+\left(5+15\right)+\left(7+13\right)+\left(9+11\right)\)

\(x=20+20+20+20+20\)

\(x=20\times5=100\)

x​ = 100

nhé bn

1+3+5+7+9+11+13+15+17+19+20=

(1+19)+(3+17)+(5+15)+(7+13)+20=

20      +20      +20     + 20     +20=100

=120 nha bạn

1+3+5+7+9+11+13+15+17+19+20

=(1+19)+(3+17)+(5+15)+(7+13)+(9+11)+20

=20+20+20+20+20+20

=20*6

=120

B=-24

B=(1+3-5-7)x3=-8x3=-24

B= -24

a; A = -1 + 3 - 5 + 7 - 9 + 11 - 13 + 15 - 17

   A = (-1 + 11) + ( 3 - 13) + (-5 + 15) + (7 - 17) - 9

   A = 10 - 10 + 10 - 10 - 9

 A = (10 - 10) + (10 - 10) - 9

 A = 0 + 0 - 9

A = -9 

b; B = 1+2-3-4+5+6-7-8+9+10-11-12+13+14-15-16+17+18-19-20

B = (1+2-3-4) + (5+6-7-8)+(9+10-11-12)+(13+14-15-16)+(17+18-19-20)

B= -4+(-4)+(-4)+(-4)+(-4) 

B= -4 . 5

B= -20