0=-16x^2+64x+15

Solution for 0=-16x^2+64x+15 equation:

0=-16x^2+64x+15

We move all terms to the left:

0-(-16x^2+64x+15)=0

We add all the numbers together, and all the variables

-(-16x^2+64x+15)=0

We get rid of parentheses

16x^2-64x-15=0

a = 16; b = -64; c = -15;
Δ = b2-4ac
Δ = -642-4·16·(-15)
Δ = 5056
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:

$\sqrt{\Delta}=\sqrt{5056}=\sqrt{64*79}=\sqrt{64}*\sqrt{79}=8\sqrt{79}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-64)-8\sqrt{79}}{2*16}=\frac{64-8\sqrt{79}}{32}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-64)+8\sqrt{79}}{2*16}=\frac{64+8\sqrt{79}}{32}
$