3500r^2+8500r-258.15=0

Solution for 3500r^2+8500r-258.15=0 equation:

3500r^2+8500r-258.15=0

a = 3500; b = 8500; c = -258.15;
Δ = b2-4ac
Δ = 85002-4·3500·(-258.15)
Δ = 75864100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{75864100}=8710$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8500)-8710}{2*3500}=\frac{-17210}{7000}
=-2+321/700
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8500)+8710}{2*3500}=\frac{210}{7000}
=3/100
$