-11=6t-5t^2

Solution for -11=6t-5t^2 equation:

-11=6t-5t^2

We move all terms to the left:

-11-(6t-5t^2)=0

We get rid of parentheses

5t^2-6t-11=0

a = 5; b = -6; c = -11;
Δ = b2-4ac
Δ = -62-4·5·(-11)
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$t_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-16}{2*5}=\frac{-10}{10}
=-1
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+16}{2*5}=\frac{22}{10}
=2+1/5
$