a) \(x=-1\Leftrightarrow\frac{7}{3a-1}=-1\)
\(\Leftrightarrow3a-1=-7\Leftrightarrow a=-2\)
b) \(x=7\Leftrightarrow\frac{7}{3a-1}=7\)
\(\Leftrightarrow3a-1=1\Leftrightarrow a=\frac{2}{3}\)
a) x = -1
7/3a - 1 = -1
7 = -3a + 1
7 - 1 = -3a
6 = -3a
6 : (-3) = a
-2 = a
=> a = -2
b) x = 7
7/3a - 1 = 7
7 = 7(3a - 1)
7 : 7 = 3a - 1
1 = 3a - 1
1 + 1 = 3a
2 = 3a
2/3 = a
=> a = 2/3
Bài giả
Ta có : \(x=\frac{7}{3a-1}\)
\(a,\text{ }x=-1\) \(\Rightarrow\text{ }7\text{ : }\left(3a-1\right)=-1\)
\(3a-1=7\text{ : }\left(-1\right)\)
\(3a-1=-7\)
\(3a=-7+1\)
\(3a=-6\)
\(a=-6\text{ : }3\)
\(a=-2\)
\(b,\text{ }x=7\) \(\Rightarrow\text{ }7\text{ : }\left(3a-1\right)=7\)
\(3a-1=7\text{ : }7\)
\(3a-1=1\)
\(3a=1+1\)
\(3a=2\)
\(a=\frac{2}{3}\)
Bài giả
Ta có : \(x=\frac{7}{3a-1}\)
\(a,\text{ }x=-1\) \(\Rightarrow\text{ }7\text{ : }\left(3a-1\right)=-1\)
\(3a-1=7\text{ : }\left(-1\right)\)
\(3a-1=-7\)
\(3a=-7+1\)
\(3a=-6\)
\(a=-6\text{ : }3\)
\(a=-2\)
\(b,\text{ }x=7\) \(\Rightarrow\text{ }7\text{ : }\left(3a-1\right)=7\)
\(3a-1=7\text{ : }7\)
\(3a-1=1\)
\(3a=1+1\)
\(3a=2\)
\(a=\frac{2}{3}\)
