7x2+100x-4=0

Solution for 7x2+100x-4=0 equation:

7x^2+100x-4=0

a = 7; b = 100; c = -4;
Δ = b2-4ac
Δ = 1002-4·7·(-4)
Δ = 10112
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:

$\sqrt{\Delta}=\sqrt{10112}=\sqrt{64*158}=\sqrt{64}*\sqrt{158}=8\sqrt{158}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(100)-8\sqrt{158}}{2*7}=\frac{-100-8\sqrt{158}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(100)+8\sqrt{158}}{2*7}=\frac{-100+8\sqrt{158}}{14}
$