-65x^2+140x+165=0

Solution for -65x^2+140x+165=0 equation:

-65x^2+140x+165=0

a = -65; b = 140; c = +165;
Δ = b2-4ac
Δ = 1402-4·(-65)·165
Δ = 62500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{62500}=250$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(140)-250}{2*-65}=\frac{-390}{-130}
=+3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(140)+250}{2*-65}=\frac{110}{-130}
=-11/13
$