-49x^2-21x=0

Solution for -49x^2-21x=0 equation:

-49x^2-21x=0

a = -49; b = -21; c = 0;
Δ = b2-4ac
Δ = -212-4·(-49)·0
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-21)-21}{2*-49}=\frac{0}{-98}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+21}{2*-49}=\frac{42}{-98}
=-3/7
$