Toán A=1+(-3)+5+(-7)+……+2019+(-2021) B=1+(-2)+3+(-4)+…..+(-2020)+2021 02/12/2021 By Vivian A=1+(-3)+5+(-7)+……+2019+(-2021) B=1+(-2)+3+(-4)+…..+(-2020)+2021
`A=1+(-3)+5+(-7)+… + 2017+(- 2019 )+2021` `A =1 – 3 + 5 – 7 + … + 2017 – 2019 + 2021` `A = ( 1 – 3) + ( 5-7) + …+ (2017 – 2019) + 2021` `A =-2 + ( -2)+ … + (-2) + 2021` `A = -2. 1010 + 2021` `A = -1010 + 2021` `A = 1011` `B=1+(-2)+3+(-4)+…+(-2020)+2021` `A = 1- 2 + 3 – 4 + … +2019 – 2020 +2021` `A = (1-2) + (3-4) + … + (2019 – 2020)+ 2021` `A = -1 + ( -1) + … + (-1) + 2021` `A = -1 . 1010 + 2021` `A = -1001` Trả lời
sai đề $A=1 − 3 + 5 − 7+. . . −2019 + 2021$$= (1 − 3) + (5 − 7)+. . +(2017 − 2019) + 2021$$= (−2) + (−2)+. . . +(−2) + 2021$$= −2.505 + 2021$$= 1011$ $B= 1 – 2 + 3 – 4 + 5 – 6 + … + 2019 – 2020 + 2021$ $= ( 1 – 2 ) + ( 3 – 4 ) + … + ( 2019 – 2020 ) + 2021 $ $= ( -1 ) + ( -1 ) + … + ( – 1 ) + 2021 $ $= ( – 1 ) . 1010 + 2021 $ $= -1010 + 2021 $ $= 1011 $ Trả lời
`A=1+(-3)+5+(-7)+… + 2017+(- 2019 )+2021`
`A =1 – 3 + 5 – 7 + … + 2017 – 2019 + 2021`
`A = ( 1 – 3) + ( 5-7) + …+ (2017 – 2019) + 2021`
`A =-2 + ( -2)+ … + (-2) + 2021`
`A = -2. 1010 + 2021`
`A = -1010 + 2021`
`A = 1011`
`B=1+(-2)+3+(-4)+…+(-2020)+2021`
`A = 1- 2 + 3 – 4 + … +2019 – 2020 +2021`
`A = (1-2) + (3-4) + … + (2019 – 2020)+ 2021`
`A = -1 + ( -1) + … + (-1) + 2021`
`A = -1 . 1010 + 2021`
`A = -1001`
sai đề
$A=1 − 3 + 5 − 7+. . . −2019 + 2021$
$= (1 − 3) + (5 − 7)+. . +(2017 − 2019) + 2021$
$= (−2) + (−2)+. . . +(−2) + 2021$
$= −2.505 + 2021$
$= 1011$
$B= 1 – 2 + 3 – 4 + 5 – 6 + … + 2019 – 2020 + 2021$
$= ( 1 – 2 ) + ( 3 – 4 ) + … + ( 2019 – 2020 ) + 2021 $
$= ( -1 ) + ( -1 ) + … + ( – 1 ) + 2021 $
$= ( – 1 ) . 1010 + 2021 $
$= -1010 + 2021 $
$= 1011 $