4.905x^2+15=18x

Solution for 4.905x^2+15=18x equation:

4.905x^2+15=18x

We move all terms to the left:

4.905x^2+15-(18x)=0

a = 4.905; b = -18; c = +15;
Δ = b2-4ac
Δ = -182-4·4.905·15
Δ = 29.7
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-18)-\sqrt{29.7}}{2*4.905}=\frac{18-\sqrt{29.7}}{9.81}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+\sqrt{29.7}}{2*4.905}=\frac{18+\sqrt{29.7}}{9.81}
$