-7x(8x-3)=-14

Solution for -7x(8x-3)=-14 equation:

-7x(8x-3)=-14

We move all terms to the left:

-7x(8x-3)-(-14)=0

We add all the numbers together, and all the variables

-7x(8x-3)+14=0

We multiply parentheses

-56x^2+21x+14=0

a = -56; b = 21; c = +14;
Δ = b2-4ac
Δ = 212-4·(-56)·14
Δ = 3577
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{3577}=\sqrt{49*73}=\sqrt{49}*\sqrt{73}=7\sqrt{73}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21)-7\sqrt{73}}{2*-56}=\frac{-21-7\sqrt{73}}{-112}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+7\sqrt{73}}{2*-56}=\frac{-21+7\sqrt{73}}{-112}
$