Toán -2/5×5/8+5/8×3/5 2/3-5/7×14/25 8x=7,8.x+25 Giúp mình với 31/07/2021 By Skylar -2/5×5/8+5/8×3/5 2/3-5/7×14/25 8x=7,8.x+25 Giúp mình với
Đáp án: `(-2)/5 . 5/8 + 5/8 . 3/5` `= 5/8 . ((-2)/5 + 3/5)` `= 5/8 . 1/5` `= 1/8` `2/3 – 5/7 . 14/25` `= 2/3 – 2/5` `= 4/15` `8x = 7,8 . x + 25` `=> 8x – 7,8x = 25` `=> 0,2x = 25` `=> x = 25 : 0,2` `=> x = 125` Vậy `x = 125` Trả lời
`a) -2/5 xx 5/8 + 5/8 xx 3/5` `= 5/8 xx (-2/5 + 3/5)` `= 5/8 xx 1/5` `= 1/8` `b) 2/3 – 5/7 xx 14/25` `= 2/3 – 2/5` `= 10/15 – 6/15` `= 4/15` `c) 8x = 7,8. x +25` `⇒ 8x – 7,8. x = 25` `⇒ 0,2. x = 25` `⇒ x = 25 : 0,2` `⇒ x = 125` `Vậy x = 125` Trả lời
Đáp án:
`(-2)/5 . 5/8 + 5/8 . 3/5`
`= 5/8 . ((-2)/5 + 3/5)`
`= 5/8 . 1/5`
`= 1/8`
`2/3 – 5/7 . 14/25`
`= 2/3 – 2/5`
`= 4/15`
`8x = 7,8 . x + 25`
`=> 8x – 7,8x = 25`
`=> 0,2x = 25`
`=> x = 25 : 0,2`
`=> x = 125`
Vậy `x = 125`
`a) -2/5 xx 5/8 + 5/8 xx 3/5`
`= 5/8 xx (-2/5 + 3/5)`
`= 5/8 xx 1/5`
`= 1/8`
`b) 2/3 – 5/7 xx 14/25`
`= 2/3 – 2/5`
`= 10/15 – 6/15`
`= 4/15`
`c) 8x = 7,8. x +25`
`⇒ 8x – 7,8. x = 25`
`⇒ 0,2. x = 25`
`⇒ x = 25 : 0,2`
`⇒ x = 125`
`Vậy x = 125`