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10:15 ; \(\dfrac{16}{9}\):\(\dfrac{16}{24}\) ; \(\dfrac{2}{3}\):\(\dfrac{1}{4}\) ; 16:(-4) ; 14:21 ; -5:15 ; 12:(-3) ; -1,2:3,6
10:15=\(\dfrac{2}{3}\) ;\(\dfrac{16}{24}\)=\(\dfrac{2}{3}\) ;16:(-4)=-4 ;14:21=\(\dfrac{2}{3}\) :-5:15=\(\dfrac{-1}{3}\) ;12:(-3)=-4
-1,2:3,6=\(\dfrac{-1}{3}\)
Ta có các tỉ lệ thức: \(\dfrac{10}{15}\)=\(\dfrac{16}{24}\)=\(\dfrac{14}{21}\)=\(\dfrac{2}{3}\) ;\(\dfrac{16}{-4}\)=\(\dfrac{12}{-3}\)=-4 ;\(\dfrac{-5}{15}\)=\(\dfrac{-1,2}{3,6}\)=\(\dfrac{-1}{3}\)
Bài 2:
a: Để x>0 thì a-3>0
=>a>3
b: Để x<0 thì a-3<0
=>a<3
c: Để x=0 thì a-3=0
=>a=3
Bài 1:
\(=\left(\dfrac{1}{3}+\dfrac{3}{5}+\dfrac{1}{15}\right)+\left(\dfrac{-3}{4}-\dfrac{2}{9}-\dfrac{1}{36}\right)+\dfrac{1}{64}\)
\(=\dfrac{5+9+1}{15}+\dfrac{-27-8-1}{36}+\dfrac{1}{64}\)
\(=\dfrac{1}{64}\)
a: \(\Leftrightarrow-\dfrac{23}{5}\cdot\dfrac{50}{23}< x< \dfrac{-13}{5}:\dfrac{21}{15}=\dfrac{-13}{5}\cdot\dfrac{5}{7}=\dfrac{-13}{7}\)
=>-10<x<-13/7
hay \(x\in\left\{-9;-8;-7;-6;-5;-4;-3;-2\right\}\)
b: \(\Leftrightarrow-\dfrac{13}{3}\cdot\dfrac{1}{3}< x< \dfrac{-2}{3}\cdot\dfrac{4-3-9}{12}\)
\(\Leftrightarrow-\dfrac{13}{9}< x< \dfrac{4}{9}\)
mà x là số nguyên
nên \(x\in\left\{-1;0\right\}\)
bài 1) ta có : \(\dfrac{2x-y}{x+y}=\dfrac{2}{3}\Leftrightarrow2\left(x+y\right)=3\left(2x-y\right)\)
\(\Leftrightarrow2x+2y=6x-3y\Leftrightarrow4x=5y\Leftrightarrow\dfrac{x}{y}=\dfrac{5}{4}\)
vậy \(\dfrac{x}{y}=\dfrac{5}{4}\)
bài 1
\(\dfrac{2x-y}{x+y}=\dfrac{2}{3}\Leftrightarrow\dfrac{2.\dfrac{x}{y}-1}{\dfrac{x}{y}+1}=\dfrac{2.\dfrac{x}{y}+2-3}{\dfrac{x}{y}+1}=2-\dfrac{3}{\dfrac{x}{y}+1}=\dfrac{2}{3}\)
\(2-\dfrac{2}{3}=\dfrac{4}{3}=\dfrac{3}{\dfrac{x}{y}+1}\)
\(\left(\dfrac{x}{y}+1\right)=\dfrac{9}{4}\Rightarrow\dfrac{x}{y}=\dfrac{9}{4}-\dfrac{4}{4}=\dfrac{5}{4}\)
1: \(\Leftrightarrow3x+4=2\)
=>3x=-2
=>x=-2/3
2: \(\Leftrightarrow7x-7=6x-30\)
=>x=-23
3: =>\(5x-5=3x+9\)
=>2x=14
=>x=7
4: =>9x+15=14x+7
=>-5x=-8
=>x=8/5
a, 1/3-3/4+3/5+1/4-2/9-1/36+1/15
=(1/3+3/5+1/15)-(3/4-1/4+2/9+1/36)
=1 - 3/4
=1/4
b, 3-1/4+2/3-5-1/3+6/5-6+7/4-3/2
=(3-5-6)-(1/4-7/4)+(2/3-1/3)+(6/5-3/2)
=-8 +3/2 +1/3 -3/10
=-97/15
5/2 hoặc 15/2
sao cứ cặp kè yuki vậy mà bài này lâu rùi cha