( 15 + 21 ) + ( 25 - 15 - 35 -21 )

=15 + 21 + 25 - 15 - 35 - 21

= ( 15 - 15 ) + ( 21 - 21 ) + (25 - 35 )

= 0 + 0 - 10 

= - 10

dễ thật -10day ban 

(15+21)+(25-15-35-25)

=(15-15)+(25-25)+21-35

=21-35

=(-14)

(15+21)+(25-15-35-21)

=(35-25)x15x21

=3150

k mk rồi mk k lại

15 + 21 + 25 - 15 - 35 - 21

= (15 - 15) + (21 - 21) + (25 - 35)

= 0 + 0 - 10

= - 10

(15+21)+(25-15-35-21)

=15+21+25-15-35-21

=[15-15]+[21-21]+[35-15]

=0+0+20

=20

(25+51)+(42-25-53-51)

= 25+51+42-25-53-51

=[25-25]+[51-51]+[42-53]

=0+0+(-11)

=-11

-5 + 11 + (-15) +21 +(-25) + 31 +...+ (-95)+101

= [(-5)+11] + [(-15)+21] + [(-25)+31]+....+[(-95)+101]

= 6+6+6+.....6

( co 10 chu so 6)

=6.10

= 60

Tran Viet Ha co 9 chu so 6 thoi

21.35-3.25.7

= 21.35-21.25

= 21.(35-25)

= 21. 10

=210

77 - 11.( 30+7)

= 11.7 -11.30 -11.7

= 11.7-11.7 -11.30

= -11.30

= -330

21.35-3.25.7=210

77-11(30+7)=-330

85(35-27)-35(85-27)=-1350

47(45-15)-47(45+15)=-2820

=-10

k nha

= -10 nha

Lời giải:

a. $=-(37+63)+[25+(-25)]+(-9)=-100+0+(-9)=-(100+9)=-109$

b. $=[1+(-3)]+[5+(-7)]+....+[21+(-23)]$

$=\underbrace{(-2)+(-2)+....+(-2)}_{6}=(-2).6=-12$

c. $=-(280+20)+[-(79+21)]=-300+(-100)=-(300+100)=-400$

d. $=[-(27+43)]+[-(208+102)]=-70+(-310)=-(70+310)=-380$

e. $=(38+120)-(12+46)=158-58=100$

f. $=9+15+11+24=(9+11)+(15+24)=20+39=59$

(-126)-[(-25)-(-126)]-(318-20)-210⁰

=(-126) - (-25) - 298 - 1 

= -101 - (-298) - 1

=197-1

=196