49x^2-28x-4=0

Solution for 49x^2-28x-4=0 equation:

49x^2-28x-4=0

a = 49; b = -28; c = -4;
Δ = b2-4ac
Δ = -282-4·49·(-4)
Δ = 1568
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:

$\sqrt{\Delta}=\sqrt{1568}=\sqrt{784*2}=\sqrt{784}*\sqrt{2}=28\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-28)-28\sqrt{2}}{2*49}=\frac{28-28\sqrt{2}}{98}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+28\sqrt{2}}{2*49}=\frac{28+28\sqrt{2}}{98}
$