Tìm x (phân số) a) 4/7*x-2/3=1/5; b) 2/9-7/8*x=1/3; c) 4/5+5/7:x=1/6 08/10/2021 Bởi Skylar Tìm x (phân số) a) 4/7*x-2/3=1/5; b) 2/9-7/8*x=1/3; c) 4/5+5/7:x=1/6
$a)$ `4/7 . x – 2/3 = 1/5` `=> 4/7 . x = 1/5 + 2/3` `=> 4/7 . x = 3/15 + 10/15` `=> 4/7 . x = 13/15` `=> x = 13/15 : 4/7` `=> x = 13/15 . 7/4` `=> x = 91/60` $b)$ `2/9 – 7/8 . x = 1/3` `=> 7/8 . x = 2/9 – 1/3` `=> 7/8 . x = 2/9 – 3/9` `=> 7/8 . x = -1/9` `=> x = -1/9 . 8/7` `=> x = -8/63` $c)$ `4/5 + 5/7 : x = 1/6` `=> 5/7 : x = 5/30 – 24/30` `=> 5/7 : x = -19/30` `=> x = 5/7 . {-30}/19` `=> x = {-150}/133` Bình luận
Đáp án: Giải thích các bước giải: $a)\dfrac{4}{7}.x-\dfrac{2}{3}=\dfrac{1}{5}$ $\dfrac{4}{7}.x=\dfrac{1}{5}+\dfrac{2}{3}$ $\dfrac{4}{7}.x=\dfrac{13}{15}$ $x=\dfrac{13}{15}:\dfrac{4}{7}$ $\to x=\dfrac{91}{60}$ $b)\dfrac{2}{9}-\dfrac{7}{8}x=\dfrac{1}{3}$$\dfrac{7}{8}x=\dfrac{-1}{9}$ $x=\dfrac{-1}{9}:\dfrac{7}{8}$ $x=\dfrac{-8}{63}$ $c)\dfrac{4}{5}+\dfrac{5}{7}:x=\dfrac{1}{6}$ $\dfrac{5}{7}:x=\dfrac{-19}{30}$ $x=\dfrac{-150}{133}$ Bình luận
$a)$
`4/7 . x – 2/3 = 1/5`
`=> 4/7 . x = 1/5 + 2/3`
`=> 4/7 . x = 3/15 + 10/15`
`=> 4/7 . x = 13/15`
`=> x = 13/15 : 4/7`
`=> x = 13/15 . 7/4`
`=> x = 91/60`
$b)$
`2/9 – 7/8 . x = 1/3`
`=> 7/8 . x = 2/9 – 1/3`
`=> 7/8 . x = 2/9 – 3/9`
`=> 7/8 . x = -1/9`
`=> x = -1/9 . 8/7`
`=> x = -8/63`
$c)$
`4/5 + 5/7 : x = 1/6`
`=> 5/7 : x = 5/30 – 24/30`
`=> 5/7 : x = -19/30`
`=> x = 5/7 . {-30}/19`
`=> x = {-150}/133`
Đáp án:
Giải thích các bước giải:
$a)\dfrac{4}{7}.x-\dfrac{2}{3}=\dfrac{1}{5}$
$\dfrac{4}{7}.x=\dfrac{1}{5}+\dfrac{2}{3}$
$\dfrac{4}{7}.x=\dfrac{13}{15}$
$x=\dfrac{13}{15}:\dfrac{4}{7}$
$\to x=\dfrac{91}{60}$
$b)\dfrac{2}{9}-\dfrac{7}{8}x=\dfrac{1}{3}$
$\dfrac{7}{8}x=\dfrac{-1}{9}$
$x=\dfrac{-1}{9}:\dfrac{7}{8}$
$x=\dfrac{-8}{63}$
$c)\dfrac{4}{5}+\dfrac{5}{7}:x=\dfrac{1}{6}$
$\dfrac{5}{7}:x=\dfrac{-19}{30}$
$x=\dfrac{-150}{133}$