`S = 1/2022 - ( 5/(2*4) + 5/(4*6) + 5/(6*8) + ... +5/(2020*2022))`
`Đặt A = 5/(2*4) + 5/(4*6) + 5/(6*8) +....+ 5/(2020*2022)`
` A/5 = 1/(2*4) + 1/(4*6) + 1/(6*8) +....+ 1/(2020*2022)`
` (2A)/5 = 2/(2*4) + 2/(4*6) + 2/(6*8) +....+ 2/(2020*2022)`
` (2A)/5 = 1/2-1/4+1/4-1/6+...+1/2020-1/2022`
` (2A)/5 = 1/2 - 1/2022`
`(2A)/5 = 1010/2022= 505/1011`
` A = ((505/1011)*5)/2 `
`A =2525/2022`
`S = 1/2022 - 2525/2022 `
`S = (-2524)/2022 = (-1262)/1011`
`Chúc ngủ ngon!`
`#KAITO#`
