72x^2-55x-7=0

Solution for 72x^2-55x-7=0 equation:

72x^2-55x-7=0

a = 72; b = -55; c = -7;
Δ = b2-4ac
Δ = -552-4·72·(-7)
Δ = 5041
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5041}=71$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-55)-71}{2*72}=\frac{-16}{144}
=-1/9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-55)+71}{2*72}=\frac{126}{144}
=7/8
$