-4x*x+5x+25=0

Solution for -4x*x+5x+25=0 equation:

-4x*x+5x+25=0

We add all the numbers together, and all the variables

5x-4x*x+25=0

Wy multiply elements

-4x^2+5x+25=0

a = -4; b = 5; c = +25;
Δ = b2-4ac
Δ = 52-4·(-4)·25
Δ = 425
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:

$\sqrt{\Delta}=\sqrt{425}=\sqrt{25*17}=\sqrt{25}*\sqrt{17}=5\sqrt{17}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-5\sqrt{17}}{2*-4}=\frac{-5-5\sqrt{17}}{-8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+5\sqrt{17}}{2*-4}=\frac{-5+5\sqrt{17}}{-8}
$