20t^2-t-1=0

Solution for 20t^2-t-1=0 equation:

20t^2-t-1=0

We add all the numbers together, and all the variables

20t^2-1t-1=0

a = 20; b = -1; c = -1;
Δ = b2-4ac
Δ = -12-4·20·(-1)
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-9}{2*20}=\frac{-8}{40}
=-1/5
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+9}{2*20}=\frac{10}{40}
=1/4
$