a*3a=7500

Solution for a*3a=7500 equation:

a*3a=7500

We move all terms to the left:

a*3a-(7500)=0

Wy multiply elements

3a^2-7500=0

a = 3; b = 0; c = -7500;
Δ = b2-4ac
Δ = 02-4·3·(-7500)
Δ = 90000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{90000}=300$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-300}{2*3}=\frac{-300}{6}
=-50
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+300}{2*3}=\frac{300}{6}
=50
$