-7x2-98x-280=0

Solution for -7x2-98x-280=0 equation:

-7x^2-98x-280=0

a = -7; b = -98; c = -280;
Δ = b2-4ac
Δ = -982-4·(-7)·(-280)
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-98)-42}{2*-7}=\frac{56}{-14}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-98)+42}{2*-7}=\frac{140}{-14}
=-10
$