giup minh bai nay voi
-1+3-5+7....+97-99
1+2-3-4+...+97+98-99-100
cam on cac bn nhieu☺☺☺☺
Cac ban giai giup minh bai nay voi
a 1+(-3)+2+(-4)+3+(-5)+...+98+(-100)
b 1+(-5)+2+(-6)+3+(-7)+...+99+(-103)
mấy bạn tinh giup mik bai nay voi
100-99+98-97.....+4-3+2-1
tra loi bai nay ho toi nhe
de bai: tinh gon
A= 1+2+22+23 ...+299+2100
B=1-2+22-23+-299+2100
B=3^100-3^99-3^98-..-3-1
B=3^100-(3^99+3^98+...+3+1)
ta có:M=3^99+3^98+..+3+1
3M=3^100+3^98+...+3^2+3
2M=3M-M=3^100+3^99+3^98+...+3^2+3-3^99+3^98+...+1
2M=3^100-1
=>B=3^100-3^100+1:2
B=0+1/2
B=1/2
bai 1 :
1) ( -213) + 186 + ( - 14 ) + 217 + 54 + ( - 49 )
2 ) - 38 . ( 25 - 4 ) + 25 . ( -4 + 38 )
3) -39 . ( 5 - 99 ) + 99 . ( 10 - 39 )
4 ) 1+ 3-5-7+9+ 11 - ....- 397 - 399
5) 1+ 2 + 2^2 + ... + 2 ^ 100
6) 3^102 - 3 ^ 100 - 3 ^ 98 -...3 ^2 - 3 ^0
cam phien cac ban lam giup minh nha
Tinh nhanh:
(-1)*(-1)^2*(-1)^3*(-1)^4*...*(-1)^99*(-1)^100
Giup minh nhe!
B=(101+100+99+98+.....+3+2+1) / (101-100+99-98+.......+3-2+1)
B=(101+100+99+98+.....+3+2+1) / (101-100+99-98+.......+3-2+1)