-30+11a+28a^2=0

Solution for -30+11a+28a^2=0 equation:

-30+11a+28a^2=0

a = 28; b = 11; c = -30;
Δ = b2-4ac
Δ = 112-4·28·(-30)
Δ = 3481
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3481}=59$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(11)-59}{2*28}=\frac{-70}{56}
=-1+1/4
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(11)+59}{2*28}=\frac{48}{56}
=6/7
$