64*x-5*x^2-195=0

Solution for 64*x-5*x^2-195=0 equation:

64x-5x^2-195=0

a = -5; b = 64; c = -195;
Δ = b2-4ac
Δ = 642-4·(-5)·(-195)
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(64)-14}{2*-5}=\frac{-78}{-10}
=7+4/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(64)+14}{2*-5}=\frac{-50}{-10}
=+5
$