-2x2+25x-42=0

Solution for -2x2+25x-42=0 equation:

-2x^2+25x-42=0

a = -2; b = 25; c = -42;
Δ = b2-4ac
Δ = 252-4·(-2)·(-42)
Δ = 289
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{289}=17$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(25)-17}{2*-2}=\frac{-42}{-4}
=10+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(25)+17}{2*-2}=\frac{-8}{-4}
=+2
$