Toán Tính giùm với ạk :v A=1/28+1/70+1/130+…+1/700 02/08/2021 By Aubrey Tính giùm với ạk :v A=1/28+1/70+1/130+…+1/700
`A=1/28+1/70+1/130+…+1/700` `⇒A = 1/(4.7) + 1/(7.10) + 1/(10.13) + …. + 1/(25.28)` `⇒A = 1/3( 3/(4.7) + 3/(7.10) + 3/(10.13) + …. + 3/(25.28) )` `⇒A=1/3(1/4 – 1/7 + …. + 1/25 – 1/28)` `⇒A=1/3(1/4 – 1/28)` `⇒A= 1/3 . 3/14` `⇒A=1/14` Trả lời
`A = 1/28 + 1/70 + 1/130 + … + 1/700` `A = 1/( 4 . 7 ) + 1/( 7 . 10 ) + … + 1/( 25 . 28 )` `A . 3 = 3/( 4 . 7 ) + 3/( 7 . 10 ) + … + 3/( 25 . 28 )` `A . 3 = 1/4 – 1/7 + 1/7 – 1/10 + … + 1/25 – 1/28` `A . 3 = 1/4 – 1/28` `A . 3 = 3/14` `A = 3/14 : 3` `A = 1/14` Trả lời
`A=1/28+1/70+1/130+…+1/700`
`⇒A = 1/(4.7) + 1/(7.10) + 1/(10.13) + …. + 1/(25.28)`
`⇒A = 1/3( 3/(4.7) + 3/(7.10) + 3/(10.13) + …. + 3/(25.28) )`
`⇒A=1/3(1/4 – 1/7 + …. + 1/25 – 1/28)`
`⇒A=1/3(1/4 – 1/28)`
`⇒A= 1/3 . 3/14`
`⇒A=1/14`
`A = 1/28 + 1/70 + 1/130 + … + 1/700`
`A = 1/( 4 . 7 ) + 1/( 7 . 10 ) + … + 1/( 25 . 28 )`
`A . 3 = 3/( 4 . 7 ) + 3/( 7 . 10 ) + … + 3/( 25 . 28 )`
`A . 3 = 1/4 – 1/7 + 1/7 – 1/10 + … + 1/25 – 1/28`
`A . 3 = 1/4 – 1/28`
`A . 3 = 3/14`
`A = 3/14 : 3`
`A = 1/14`