4=9k2

Solution for 4=9k2 equation:

4=9k^2

We move all terms to the left:

4-(9k^2)=0

a = -9; b = 0; c = +4;
Δ = b2-4ac
Δ = 02-4·(-9)·4
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-12}{2*-9}=\frac{-12}{-18}
=2/3
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+12}{2*-9}=\frac{12}{-18}
=-2/3
$