0=-49k^2+7k+20

Solution for 0=-49k^2+7k+20 equation:

0=-49k^2+7k+20

We move all terms to the left:

0-(-49k^2+7k+20)=0

We add all the numbers together, and all the variables

-(-49k^2+7k+20)=0

We get rid of parentheses

49k^2-7k-20=0

a = 49; b = -7; c = -20;
Δ = b2-4ac
Δ = -72-4·49·(-20)
Δ = 3969
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3969}=63$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-63}{2*49}=\frac{-56}{98}
=-4/7
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+63}{2*49}=\frac{70}{98}
=5/7
$