Tìm x a) x + 3/4 = -1/12 b) | 3/8 – x | = 5/6 c) x+5 / 6 = -2/3 d) -3/4 : ( 2 và 1/4 . x – 25% ) = 3 08/07/2021 Bởi Reese Tìm x a) x + 3/4 = -1/12 b) | 3/8 – x | = 5/6 c) x+5 / 6 = -2/3 d) -3/4 : ( 2 và 1/4 . x – 25% ) = 3
`\text{a)}` `x +3/4 = {-1}/12` `-> x = {-1}/12 -3/4` `-> x = {-1}/12 – 9/12` `-> x = {-5}/6` Vậy `x = {-5}/6` `\text{b)}` `|3/8-x| =5/6` `->` \(\left[ \begin{array}{l}\dfrac{3}{8}- x = \dfrac{5}{6}\\\dfrac{3}{8}- x = \dfrac{-5}{6}\end{array} \right.\) `->` \(\left[ \begin{array}{l}x= \dfrac{-11}{24}\\x= \dfrac{29}{24}\end{array} \right.\) Vậy `x \in { {-11}/24 ; 29/24 }` `\text{c)}` `x +5/6 = {-2}/3` `-> x = {-2}/3 – 5/6` `-> x = {-3}/2` Vậy `x = {-3}/2` `\text{d)}` `{-3}/4 : (2 1/4x – 25% ) =3` `-> {-3}/4 : ( 9/4x – 1/4 ) =3` `-> 9/4x – 1/4 = {-3}/4 . 1/3` `-> 9/4x -1/4 = {-1}/4` `-> 9/4x =0` `-> x =0` Vậy `x =0` Bình luận
Đáp án+Giải thích các bước giải: `a)` `x+3/4=-1/12` `→x=-1/12-3/4` `→x=-1/12-9/12` `→x=-10/12` `→x=-5/6` Vậy `x=-5/6` `b)` `|3/8-x|=5/6` TH 1: `3/8-x=5/6` `→x=3/8-5/6` `→x=-11/24` TH 2: `3/8-x=-5/6` `→x=3/8+5/6` `→29/24` Vậy `x∈\{-11/24;29/24\}` `c)` Đề 1: `x+5/6=-2/3` `→x=-2/3-5/6` `→x=-3/2` Vậy `x=-3/2` Đề 2: `(x+5)/6=-2/3` `→3.(x+5)=-2.6` `→3.(x+5)=-12` `→3x+15=-12` `→3x=-12-15` `→3x=-27` `→x=-9` Vậy `x=-9` `d)` `-3/4:(2(1)/4x-25%)=3` `→-3/4:(9/4x-1/4)=3` `→9/4x-1/4=-3/4:3` `→9/4x-1/4=-1/4` `→9/4x=-1/4+1/4` `→9/4x=0` `→x=0` Vậy `x=0` Bình luận
`\text{a)}`
`x +3/4 = {-1}/12`
`-> x = {-1}/12 -3/4`
`-> x = {-1}/12 – 9/12`
`-> x = {-5}/6`
Vậy `x = {-5}/6`
`\text{b)}`
`|3/8-x| =5/6`
`->` \(\left[ \begin{array}{l}\dfrac{3}{8}- x = \dfrac{5}{6}\\\dfrac{3}{8}- x = \dfrac{-5}{6}\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x= \dfrac{-11}{24}\\x= \dfrac{29}{24}\end{array} \right.\)
Vậy `x \in { {-11}/24 ; 29/24 }`
`\text{c)}`
`x +5/6 = {-2}/3`
`-> x = {-2}/3 – 5/6`
`-> x = {-3}/2`
Vậy `x = {-3}/2`
`\text{d)}`
`{-3}/4 : (2 1/4x – 25% ) =3`
`-> {-3}/4 : ( 9/4x – 1/4 ) =3`
`-> 9/4x – 1/4 = {-3}/4 . 1/3`
`-> 9/4x -1/4 = {-1}/4`
`-> 9/4x =0`
`-> x =0`
Vậy `x =0`
Đáp án+Giải thích các bước giải:
`a)`
`x+3/4=-1/12`
`→x=-1/12-3/4`
`→x=-1/12-9/12`
`→x=-10/12`
`→x=-5/6`
Vậy `x=-5/6`
`b)`
`|3/8-x|=5/6`
TH 1:
`3/8-x=5/6`
`→x=3/8-5/6`
`→x=-11/24`
TH 2:
`3/8-x=-5/6`
`→x=3/8+5/6`
`→29/24`
Vậy `x∈\{-11/24;29/24\}`
`c)`
Đề 1:
`x+5/6=-2/3`
`→x=-2/3-5/6`
`→x=-3/2`
Vậy `x=-3/2`
Đề 2:
`(x+5)/6=-2/3`
`→3.(x+5)=-2.6`
`→3.(x+5)=-12`
`→3x+15=-12`
`→3x=-12-15`
`→3x=-27`
`→x=-9`
Vậy `x=-9`
`d)`
`-3/4:(2(1)/4x-25%)=3`
`→-3/4:(9/4x-1/4)=3`
`→9/4x-1/4=-3/4:3`
`→9/4x-1/4=-1/4`
`→9/4x=-1/4+1/4`
`→9/4x=0`
`→x=0`
Vậy `x=0`