6=-4.9t^2+8.1t+36=-4.9t^2+8.1t+3

Solution for 6=-4.9t^2+8.1t+36=-4.9t^2+8.1t+3 equation:

6=-4.9t^2+8.1t+36=-4.9t^2+8.1t+3

We move all terms to the left:

6-(-4.9t^2+8.1t+36)=0

We get rid of parentheses

4.9t^2-8.1t-36+6=0

We add all the numbers together, and all the variables

4.9t^2-8.1t-30=0

a = 4.9; b = -8.1; c = -30;
Δ = b2-4ac
Δ = -8.12-4·4.9·(-30)
Δ = 653.61
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{-(-8.1)-\sqrt{653.61}}{2*4.9}=\frac{8.1-\sqrt{653.61}}{9.8}
$
$t_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8.1)+\sqrt{653.61}}{2*4.9}=\frac{8.1+\sqrt{653.61}}{9.8}
$