10y+5y^2=315

Solution for 10y+5y^2=315 equation:

10y+5y^2=315

We move all terms to the left:

10y+5y^2-(315)=0

a = 5; b = 10; c = -315;
Δ = b2-4ac
Δ = 102-4·5·(-315)
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(10)-80}{2*5}=\frac{-90}{10}
=-9
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(10)+80}{2*5}=\frac{70}{10}
=7
$