-9.8(x)^2+15=5

Solution for -9.8(x)^2+15=5 equation:

-9.8(x)^2+15=5

We move all terms to the left:

-9.8(x)^2+15-(5)=0

We add all the numbers together, and all the variables

-9.8x^2+10=0

a = -9.8; b = 0; c = +10;
Δ = b2-4ac
Δ = 02-4·(-9.8)·10
Δ = 392
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{392}=\sqrt{196*2}=\sqrt{196}*\sqrt{2}=14\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-14\sqrt{2}}{2*-9.8}=\frac{0-14\sqrt{2}}{-19.6}
=-\frac{14\sqrt{2}}{-19.6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+14\sqrt{2}}{2*-9.8}=\frac{0+14\sqrt{2}}{-19.6}
=\frac{14\sqrt{2}}{-19.6}
$