Question

[Nguyễn Thị Xuân Phương]

Bài 1: 

a) 2/3.x+4=-12

b) 3/4+1/4 : x  =  -3

c) x+1/10  +  x+1/11  +  x+1/12  =  x+1/13  +  x+1/14

d) x+4/2017  +  x+3/2018  =  x+2/2019  +  x+1/2020

Answer 1

[Đức Phạm]

c)\(\frac{x+1}{10}+\frac{x+1}{11}+\frac{x+1}{12}=\frac{x+1}{13}+\frac{x+1}{14}\)

\(\Leftrightarrow\frac{x+1}{10}+\frac{x+1}{11}+\frac{x+1}{12}-\frac{x+1}{13}-\frac{x+1}{14}=0\)

\(\Leftrightarrow\left(x+1\right)\cdot\left(\frac{1}{10}+\frac{1}{11}+\frac{1}{12}-\frac{1}{13}-\frac{1}{14}\right)=0\)

\(\Leftrightarrow x+1=0\cdot\left(\frac{1}{10}+\frac{1}{11}+\frac{1}{12}-\frac{1}{13}-\frac{1}{13}\right)\)

\(\Leftrightarrow x+1=0\)

\(\Leftrightarrow x=-1\)

d) \(\frac{x+4}{2017}+\frac{x+3}{2018}=\frac{x+2}{2019}+\frac{x+1}{2020}\)

\(\Leftrightarrow\left(\frac{x+4}{2017}+1\right)+\left(\frac{x+3}{2018}+1\right)=\left(\frac{x+2}{2019}+1\right)+\left(\frac{x+1}{2020}\right)\)

\(\Leftrightarrow\frac{x+2021}{2017}+\frac{x+2021}{2018}-\frac{x+2021}{2019}-\frac{x+2021}{2020}=0\)

\(\Leftrightarrow\left(x+2021\right)\cdot\left(\frac{1}{2017}+\frac{1}{2018}-\frac{1}{2019}-\frac{1}{2020}\right)=0\)

\(\Leftrightarrow x+2021=0\)

\(\Leftrightarrow x=-2021\)

Answer 2

[Nguyễn Phương Thảo]

a) 2/3.X+4=-12

2/3.X=-12-4

2/3.X=-16

x=-16:2/3

x=-16.3/2

x=-24

vậy x=-24

B) 3/4+1/4:X=-3

1/4:X=-3-3/4

1/4:X=-15/4

X=1/4:-15/4

X=1/4.4/-15

X=-1/15

VẬY X=-1/15

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