40x^2+70x+15=0

Solution for 40x^2+70x+15=0 equation:

40x^2+70x+15=0

a = 40; b = 70; c = +15;
Δ = b2-4ac
Δ = 702-4·40·15
Δ = 2500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2500}=50$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(70)-50}{2*40}=\frac{-120}{80}
=-1+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(70)+50}{2*40}=\frac{-20}{80}
=-1/4
$