25p^2-20p-21=0

Solution for 25p^2-20p-21=0 equation:

25p^2-20p-21=0

a = 25; b = -20; c = -21;
Δ = b2-4ac
Δ = -202-4·25·(-21)
Δ = 2500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$p_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$p_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2500}=50$
$p_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-50}{2*25}=\frac{-30}{50}
=-3/5
$
$p_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+50}{2*25}=\frac{70}{50}
=1+2/5
$