Question

tìm a để đa thức ax-1/2 có nghiệm x=1/3

 

Answer 1

 Ta có \(ax-\dfrac{1}{2}=0\) khi \(x=\dfrac{1}{3}\)

\(\Leftrightarrow\dfrac{1}{3}a-\dfrac{1}{2}=0\)

\(\Leftrightarrow\dfrac{1}{3}a=\dfrac{1}{2}\)

\(\Leftrightarrow a=\dfrac{1}{2}:\dfrac{1}{3}\)

\(\Leftrightarrow a=\dfrac{3}{2}\)

Answer 2

Ta có :

`ax -1/2=0` mà `x=1/3`

`-> a . 1/3 -1/2=0`

`=> a . 1.3 =0+1/2`

`=> a . 1.3 =1/2`

`=> a= 1/2 : 1/3`

`=>a= 1/2 xx 3`

`=>x=3/2`