no.21 caranya kayak apa ya?

[tex]a x^{2} +bx+c=0
\alpha + \beta = -b/a
=-1/k
\alpha . \beta = c/a=(-2k-1)/k[/tex]
[tex]a x^{2} +bx+c=0

\alpha + \beta = -b/a =-1/k

\alpha . \beta = c/a= \frac{-2k-1}{k}

( 1/ \alpha) +(1/ \beta )=1/5

\frac{ \alpha + \beta }{ \alpha . \beta } =1/5

\frac{-1/k}{(-2k-1)/k} =1/5
2k+1=5
2k=4
K=2[/tex]