77r^2+8r-45=0

Solution for 77r^2+8r-45=0 equation:

77r^2+8r-45=0

a = 77; b = 8; c = -45;
Δ = b2-4ac
Δ = 82-4·77·(-45)
Δ = 13924
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{13924}=118$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-118}{2*77}=\frac{-126}{154}
=-9/11
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+118}{2*77}=\frac{110}{154}
=5/7
$