Question 891099
{{{highlight_green(2x^2-kx+5=0)}}}  want equal roots, meaning discriminant is 0.


{{{(-k)^2-4*2*5=0}}}
{{{k^2-40=0}}}
{{{k^2=40}}}
{{{k=0+- sqrt(2*2*5)}}}
{{{highlight(k=0+- 2sqrt(5))}}}



(The 0 is included only to allow site rendering; otherwise is unnecessary.)