8x^2+7x-55=0

Solution for 8x^2+7x-55=0 equation:

8x^2+7x-55=0

a = 8; b = 7; c = -55;
Δ = b2-4ac
Δ = 72-4·8·(-55)
Δ = 1809
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:

$\sqrt{\Delta}=\sqrt{1809}=\sqrt{9*201}=\sqrt{9}*\sqrt{201}=3\sqrt{201}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-3\sqrt{201}}{2*8}=\frac{-7-3\sqrt{201}}{16}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+3\sqrt{201}}{2*8}=\frac{-7+3\sqrt{201}}{16}
$