a)(83+234)-(234-17)=83+234-234+17=(83+17)+(234-234)=100+0=100

b)(401-9876)+(9876-403)=401-9876+9876-403=(401-403)-(9876-9876)=-2+0=-2

c)(91-99-98)-(-99-98)=91-99-98+99+98=91-(99-99)-(98-98)=91-0-0=91

giúp mình nha chiều nay mình đi hok rồi

A=100-99+98-97+...+4-3+2-1

=1+1+...+1

Số số 1 là (100-2):2+1=50

vậy A= 50.1=50

B=1-2-3+4-5-6+...+97-98-99+100

=(1+4+...+100)-(2+5+...+98)-(3+6...+99)

=(100-1).34:2 - (98+2).33:2 - (99+3) .33:2

=99.34:2-100.33:2-102.33:2

=-1650

a) 234 + 177 + 16 + 23 = (234 + 16) + (177 + 23) = 250 + 200 = 450

b) 1 + 2 + 3 + 97 + 98 + 99 = (1 + 99) + (2 + 98) + (3 + 97) = 100 + 100 + 100 = 300

ko phải tính nhanh

Trả lời :

A.12345+6789 = 19134

B.9876+54321 = 64097

C. 234+567 = 801

~ HT ~

19314

64197

801

(91-99+98)-(-99+98)=91-99+98+99-98=91

(99-98+97)-(99+97+98)=99-98+97-99-97-98=(-98)*2=-196

1. (91 - 99 + 98) - (-99 + 98)

= 91 - 99 + 98 + 99 - 98

= (-99 + 99) + (98 - 98) + 91

= 0 + 0 + 91

= 91

2. (99 - 98 + 97) - (99 + 97 + 98)

= 99 - 98 + 97 - 99 - 97 - 98

= (99 - 99) + (97 - 97) + (-98 - 98)

= 0 + 0 + (-196)

= -196

109

5

28944 

103

9876 : 90 = \(\dfrac{1646}{5}\).

543 : 98 = \(\dfrac{543}{98}.\)

432 x 67 = 28944.

8976 : 87 = \(\dfrac{2992}{29}.\)

9876:90= 1646/15

543:98= 543/98

432X67= 28944

8976:87= 2992/29

B=(1-2-3+4)+(5-6-7+8)+...+(97-98-99+100)

B=0+0+..+0

B=0

C=2^100-(2^99+2^98+2^97+...+1)

đặt D=2^99+2^98+2^97+...+1

=>D=2^100-1

=>C=2^100-(2^100-1)=1

bai toan nay giai dai lam