(3x)(5x/2)=180

Solution for (3x)(5x/2)=180 equation:

(3x)(5x/2)=180

We move all terms to the left:

(3x)(5x/2)-(180)=0

We add all the numbers together, and all the variables

3x(+5x/2)-180=0

We multiply parentheses

15x^2-180=0

a = 15; b = 0; c = -180;
Δ = b2-4ac
Δ = 02-4·15·(-180)
Δ = 10800
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{10800}=\sqrt{3600*3}=\sqrt{3600}*\sqrt{3}=60\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-60\sqrt{3}}{2*15}=\frac{0-60\sqrt{3}}{30}
=-\frac{60\sqrt{3}}{30}
=-2\sqrt{3}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+60\sqrt{3}}{2*15}=\frac{0+60\sqrt{3}}{30}
=\frac{60\sqrt{3}}{30}
=2\sqrt{3}
$