a) S1 = 2 – 4 + 6 – 8 + …+ 2018- 2020 b) S2 = 2 – 4 – 6 + 8 + 10 – 12 – 14 + 16 + …+ 1994 – 1996 – 1998 + 2000 01/12/2021 Bởi Emery a) S1 = 2 – 4 + 6 – 8 + …+ 2018- 2020 b) S2 = 2 – 4 – 6 + 8 + 10 – 12 – 14 + 16 + …+ 1994 – 1996 – 1998 + 2000
a) S1 = 2 – 4 + 6 – 8 + … + 2018 – 2020 = ( 2 – 4 ) + ( 6 – 8 ) + … + ( 2018 – 2020 ) (có 505 nhóm) = -2 + (-2) + … + (-2) = -2 . 505 = -101 Vậy S1 = -101. b) S2 = 2 – 4 – 6 + 8 + 10 – 12 – 14 + 16 + … + 1994 – 1996 – 1998 + 2000 = ( 2 – 4 – 6 + 8 ) + ( 10 – 12 – 14 + 16 ) + … + ( 1994 – 1996 – 1998 + 2000 ) = 0 + 0 + … + 0 = 0 Vậy S2 = 0 ~~~ Rất vui khi được giúp bạn ~~~ Bình luận
`a,S1=2-4+6-8+…+2018-2020` `=(2-4)+(6-8)+…+(2018-2020)` `=(-2)+(-2)+…+(-2)` `=(-2).1010` `=-2020` `b,S2= 2-4-6+8 +10-12-14+16+…+1994-1996-1998+2000` `=(2-4-6+8)+(1–12-14+16)+…+(1994-1996-1998+2000)` `=0+0+…+0` `=0` ~ Học tốt ~ Bình luận
a) S1 = 2 – 4 + 6 – 8 + … + 2018 – 2020
= ( 2 – 4 ) + ( 6 – 8 ) + … + ( 2018 – 2020 ) (có 505 nhóm)
= -2 + (-2) + … + (-2)
= -2 . 505 = -101
Vậy S1 = -101.
b) S2 = 2 – 4 – 6 + 8 + 10 – 12 – 14 + 16 + … + 1994 – 1996 – 1998 + 2000
= ( 2 – 4 – 6 + 8 ) + ( 10 – 12 – 14 + 16 ) + … + ( 1994 – 1996 – 1998 + 2000 )
= 0 + 0 + … + 0 = 0
Vậy S2 = 0
~~~ Rất vui khi được giúp bạn ~~~
`a,S1=2-4+6-8+…+2018-2020`
`=(2-4)+(6-8)+…+(2018-2020)`
`=(-2)+(-2)+…+(-2)`
`=(-2).1010`
`=-2020`
`b,S2= 2-4-6+8 +10-12-14+16+…+1994-1996-1998+2000`
`=(2-4-6+8)+(1–12-14+16)+…+(1994-1996-1998+2000)`
`=0+0+…+0`
`=0`
~ Học tốt ~