Question

Remer 1) 5k? + 10k + 6 = 0

Answer 1

Ignoring the "?" in your question:

$5k+10k+6=0 \iff 15k+6=0 \iff k=-\dfrac{6}{15}$

If the "?" is a squared symbol that wasn't caught:

$5k^2+10k+6=0$

Use the quadratic formula

$x_{1,2}=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$

to get the solutions:

$x_{1,2}=\dfrac{-10\pm\sqrt{100-120}}{10}$

as you can see, the discriminant is negative, so the equation has no solution.