-25a^2+35a+6=0

Solution for -25a^2+35a+6=0 equation:

-25a^2+35a+6=0

a = -25; b = 35; c = +6;
Δ = b2-4ac
Δ = 352-4·(-25)·6
Δ = 1825
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1825}=\sqrt{25*73}=\sqrt{25}*\sqrt{73}=5\sqrt{73}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(35)-5\sqrt{73}}{2*-25}=\frac{-35-5\sqrt{73}}{-50}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(35)+5\sqrt{73}}{2*-25}=\frac{-35+5\sqrt{73}}{-50}
$