\(15:x=5\\ x=15:5\\ x=3\)
\(\dfrac{x}{4}=3\\ x=3\times4\\ x=12\)
\(\dfrac{21}{x}=7\\ x=\dfrac{21}{7}\\ x=3\)
\(a,x=15:5\\ x=3\\ b,\dfrac{x}{4}=3\\ \dfrac{x}{4}=\dfrac{12}{4}\\ x=12\\ c,đkx\ne0;\dfrac{21}{x}=7\\ \dfrac{21}{x}=\dfrac{21}{3}\\ x=3\left(thoamanđk\right)\)
\(15:x=5\)\(\Rightarrow x=15:5=3\)
\(\dfrac{x}{4}=3\Rightarrow\dfrac{x}{4}=\dfrac{12}{4}\Rightarrow x=12\)
\(\dfrac{21}{x}=7\Rightarrow x=21:7=3\)
\(a,x=15:5=3\)
Vậy \(x=3\)
\(b,x=3.4=12\)
Vậy \(x=12\)
\(c,x=21:7=3\)
Vậy \(x=3\)
\(15:x=5\)
\(x=15:5\)
\(x=5\)
\(x:4=3\)
\(x=3.4\)
\(x=12\)
\(21:x=7\)
\(x=21:7\)
\(x=3\)
15:x=5x=15:5x=315:x=5x=15:5x=3
21x=7x=217x=3
\(15:x=5\)
\(x=15:5=3\)
b)
\(\dfrac{x}{4}=3\)
\(\dfrac{x}{4}=\dfrac{3}{1}=>\dfrac{x}{4}=\dfrac{12}{4}\)
\(=>x=12\)
c)
\(\dfrac{21}{x}=7=>\dfrac{21}{x}=\dfrac{7}{1}=>\dfrac{21}{x}=\dfrac{21}{3}\)
\(=>x=3\)
15:x=5
<=>x=15:5
<=>x=3
x/4=3
<=>x/4=12/4
<=>x=12
21/x=7
<=>21/x=21/3
<=>x=3
