4x(7x-2)=76

Solution for 4x(7x-2)=76 equation:

4x(7x-2)=76

We move all terms to the left:

4x(7x-2)-(76)=0

We multiply parentheses

28x^2-8x-76=0

a = 28; b = -8; c = -76;
Δ = b2-4ac
Δ = -82-4·28·(-76)
Δ = 8576
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:

$\sqrt{\Delta}=\sqrt{8576}=\sqrt{64*134}=\sqrt{64}*\sqrt{134}=8\sqrt{134}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-8\sqrt{134}}{2*28}=\frac{8-8\sqrt{134}}{56}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+8\sqrt{134}}{2*28}=\frac{8+8\sqrt{134}}{56}
$