t2-5t-15=0

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

t2-5t-15=0

We add all the numbers together, and all the variables

t^2-5t-15=0

a = 1; b = -5; c = -15;
Δ = b2-4ac
Δ = -52-4·1·(-15)
Δ = 85
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-\sqrt{85}}{2*1}=\frac{5-\sqrt{85}}{2}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+\sqrt{85}}{2*1}=\frac{5+\sqrt{85}}{2}
$