Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
B2"
`a)3/4+1/2-1/4`
`=3/4-1/4+1/2`
`=1/2+1/2=1`
`b)(-2)/3*5/7+(-2)/3*2/7+5/3`
`=(-2)/3*(5/7+2/7)+5/3`
`=-2/3+5/3=1`
`c)(-5)/9+5/9:(1 2/3-2 1/6)`
`=(-5)/9+5/9:(5/3-13/6)`
`=(-5)/9+5/9:(-3)/6`
`=(-5)/9+5/9*(-2)`
`=5/9*(-1-2)`
`=5/9*(-3)=-5/3`
b3:
`a)x*3/6=2/3`
`=>x*1/2=2/3`
`=>x=4/3`
`b)x/150=5/6*(-7)/25`
`=>x/150=(-7)/(6*5)=-7/30`
`=>x/150=(-35)/150`
`=>x=-35`
`c)1/2x+3/5x=3`
`=>11/10x=3`
`=>x=3*10/11=30/11`
1: \(x=\dfrac{3}{4}-\dfrac{2}{4}=\dfrac{1}{4}\)
2: \(x=\dfrac{2}{11}+\dfrac{1}{5}=\dfrac{10+11}{55}=\dfrac{21}{55}\)
x đầu tiên sồ nào cũng đc nhưng x thứ hai phải là 256
\(\dfrac{x+1}{2021}+\dfrac{x+2}{2020}+\dfrac{x+3}{2019}=-3\)
\(\Leftrightarrow\left(\dfrac{x+1}{2021}+1\right)+\left(\dfrac{x+2}{2020}+1\right)+\left(\dfrac{x+3}{2019}+1\right)=0\)
\(\Leftrightarrow\dfrac{x+1+2021}{2021}+\dfrac{x+2+2020}{2020}+\dfrac{x+3+2019}{2019}=0\)
\(\Leftrightarrow\dfrac{x+2022}{2021}+\dfrac{x+2022}{2020}+\dfrac{x+2022}{2019}=0\)
\(\Leftrightarrow\left(x+2022\right)\left(\dfrac{1}{2021}+\dfrac{1}{2020}+\dfrac{1}{2019}\right)=0\)
\(\Leftrightarrow x+2022=0\)
\(\Leftrightarrow x=-2022\)
Vậy \(S=\left\{-2022\right\}\)
`[x+1]/2021+[x+2]/2020+[x+3]/2019=-3`
`=>[x+1]/2021+1+[x+2]/2020+1+[x+3]/2019+1=-3+1+1+1`
`=>[x+1+2021]/2021+[x+2+2020]/2020+[x+3+2019]/2019=0`
`=>[x+2022]/2021+[x+2022]/2020+[x+2022]/2019=0`
`=>(x+2022)(1/2021+1/2020+1/2019)=0`
Mà `1/2021+1/2020+1/2019 \ne 0`
`=>x+2022=0`
`=>x=-2022`
Vậy `x=-2022`
a: \(=\left(\dfrac{10}{3}+\dfrac{5}{2}\right):\left(\dfrac{19}{6}-\dfrac{21}{5}\right)-\dfrac{11}{31}\)
\(=\dfrac{35}{6}:\dfrac{95-126}{30}-\dfrac{11}{31}\)
\(=\dfrac{35}{6}\cdot\dfrac{30}{-31}-\dfrac{11}{31}\)
\(=\dfrac{-35\cdot5}{31}-\dfrac{11}{31}=\dfrac{-186}{31}=-6\)
b: \(=\left(-8\right)\cdot\dfrac{1}{2}:\left(\dfrac{9}{4}-\dfrac{7}{6}\right)=-4:\dfrac{27-14}{12}=\dfrac{-4\cdot12}{13}=\dfrac{-48}{13}\)
Số tiền Nam mua sách: \(320000\times\dfrac{1}{4}=80000\) (đồng)
Số tiền Nam mua vở: \(90000:\dfrac{2}{3}=135000\) (đồng)
Số tiền Nam mua dụng cụ học tập: \(320000-\left(80000+135000\right)=105000\) (đồng)