0=5t2-15t+5

Solution for 0=5t2-15t+5 equation:

0=5t^2-15t+5

We move all terms to the left:

0-(5t^2-15t+5)=0

We add all the numbers together, and all the variables

-(5t^2-15t+5)=0

We get rid of parentheses

-5t^2+15t-5=0

a = -5; b = 15; c = -5;
Δ = b2-4ac
Δ = 152-4·(-5)·(-5)
Δ = 125
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{125}=\sqrt{25*5}=\sqrt{25}*\sqrt{5}=5\sqrt{5}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-5\sqrt{5}}{2*-5}=\frac{-15-5\sqrt{5}}{-10}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+5\sqrt{5}}{2*-5}=\frac{-15+5\sqrt{5}}{-10}
$