-7x2=-84x

Solution for -7x2=-84x equation:

-7x^2=-84x

We move all terms to the left:

-7x^2-(-84x)=0

We get rid of parentheses

-7x^2+84x=0

a = -7; b = 84; c = 0;
Δ = b2-4ac
Δ = 842-4·(-7)·0
Δ = 7056
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7056}=84$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(84)-84}{2*-7}=\frac{-168}{-14}
=+12
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(84)+84}{2*-7}=\frac{0}{-14}
=0
$