21k-0,7k^2=0

Solution for 21k-0,7k^2=0 equation:

21k-0.7k^2=0

a = -0.7; b = 21; c = 0;
Δ = b2-4ac
Δ = 212-4·(-0.7)·0
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21)-21}{2*-0.7}=\frac{-42}{-1.4}
=+30
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+21}{2*-0.7}=\frac{0}{-1.4}
=0
$