2.5t^2+30t+30=0

Solution for 2.5t^2+30t+30=0 equation:

2.5t^2+30t+30=0

a = 2.5; b = 30; c = +30;
Δ = b2-4ac
Δ = 302-4·2.5·30
Δ = 600
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:

$\sqrt{\Delta}=\sqrt{600}=\sqrt{100*6}=\sqrt{100}*\sqrt{6}=10\sqrt{6}$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(30)-10\sqrt{6}}{2*2.5}=\frac{-30-10\sqrt{6}}{5}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(30)+10\sqrt{6}}{2*2.5}=\frac{-30+10\sqrt{6}}{5}
$