20y2-43y+21=0

Solution for 20y2-43y+21=0 equation:

20y^2-43y+21=0

a = 20; b = -43; c = +21;
Δ = b2-4ac
Δ = -432-4·20·21
Δ = 169
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{169}=13$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-43)-13}{2*20}=\frac{30}{40}
=3/4
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-43)+13}{2*20}=\frac{56}{40}
=1+2/5
$