100x^2-15x-280=0

Solution for 100x^2-15x-280=0 equation:

100x^2-15x-280=0

a = 100; b = -15; c = -280;
Δ = b2-4ac
Δ = -152-4·100·(-280)
Δ = 112225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{112225}=335$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-335}{2*100}=\frac{-320}{200}
=-1+3/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+335}{2*100}=\frac{350}{200}
=1+3/4
$