\(\frac{1}{a+2}=\frac{2}{a+6}\)
\(\Rightarrow x+6=2\left(a+2\right)\)
\(\Rightarrow x+6=2x+4\)
\(\Rightarrow-x=-2\)
\(\Rightarrow x=2\)
a) \(\frac{1}{a+2}=\frac{2}{a+6}\)
=> a + 6 = 2(a + 2)
=> a + 6 = 2a + 4
=> a - 2a = 4 - 6
=> -a = -2
=> a = 2
c) \(\frac{3a-7}{a-1}=2\)
=> 3a - 7 = 2(a - 1)
=> 3a - 7 = 2a - 2
=> 3a - 2a = -2 + 7
=> a = 5
1a, nhân chéo lên
a+6=2a+4
2a-a=6-4
a=2
b, nhân chéo lên ta đc:
3a-7=2a-2
3a-2a=-2+7
a=5
Vậy...
c, ...
4a-2=18-a
4a+a=18+2
5a=20
a=4
kl:/....
d, 9a+3=18+4a
9a-4a=18-3
5a=15
a=3
kl:...
c) \(\frac{2a-1}{18-a}=\frac{1}{2}\)
=> (2a - 1).2 = 18 - a
=> 4a - 2 = 18 - a
=> 4a + a = 18 + 2
=> 5a = 20
=> a = 20 : 5
=> a = 4
d) \(\frac{3a+1}{2}=\frac{9+2a}{3}\)
=> (3a + 1).3 = 2(9 + 2a)
=> 9a + 3 = 18 + 4a
=> 9a - 4a = 18 - 3
=> 5a = 15
=> a = 15 : 5
=> a = 3
a)1/a+2=2/a+6
a+6=2(a+2)
2a-a+4-6=0
a=2
b)3a-7/a-1=2
3a-7=2a-1
a=6
c)2a-1/18-a=1/2
4a-2=18-a
5a=20
a=4
d)3a+1/2=9+2a/3
9a+3=18+4a
5a=15
a=3
