49=100k^2

Solution for 49=100k^2 equation:

49=100k^2

We move all terms to the left:

49-(100k^2)=0

a = -100; b = 0; c = +49;
Δ = b2-4ac
Δ = 02-4·(-100)·49
Δ = 19600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{19600}=140$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-140}{2*-100}=\frac{-140}{-200}
=7/10
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+140}{2*-100}=\frac{140}{-200}
=-7/10
$