-4.9x^2+15x=-30

Solution for -4.9x^2+15x=-30 equation:

-4.9x^2+15x=-30

We move all terms to the left:

-4.9x^2+15x-(-30)=0

We add all the numbers together, and all the variables

-4.9x^2+15x+30=0

a = -4.9; b = 15; c = +30;
Δ = b2-4ac
Δ = 152-4·(-4.9)·30
Δ = 813
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{-(15)-\sqrt{813}}{2*-4.9}=\frac{-15-\sqrt{813}}{-9.8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+\sqrt{813}}{2*-4.9}=\frac{-15+\sqrt{813}}{-9.8}
$