a^2+5a=70

Solution for a^2+5a=70 equation:

a^2+5a=70

We move all terms to the left:

a^2+5a-(70)=0

a = 1; b = 5; c = -70;
Δ = b2-4ac
Δ = 52-4·1·(-70)
Δ = 305
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-\sqrt{305}}{2*1}=\frac{-5-\sqrt{305}}{2}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+\sqrt{305}}{2*1}=\frac{-5+\sqrt{305}}{2}
$