X*2,5x=720

Solution for X*2,5x=720 equation:

X*2.5X=720

We move all terms to the left:

X*2.5X-(720)=0

Wy multiply elements

2X^2-720=0

a = 2; b = 0; c = -720;
Δ = b2-4ac
Δ = 02-4·2·(-720)
Δ = 5760
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:

$\sqrt{\Delta}=\sqrt{5760}=\sqrt{576*10}=\sqrt{576}*\sqrt{10}=24\sqrt{10}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-24\sqrt{10}}{2*2}=\frac{0-24\sqrt{10}}{4}
=-\frac{24\sqrt{10}}{4}
=-6\sqrt{10}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+24\sqrt{10}}{2*2}=\frac{0+24\sqrt{10}}{4}
=\frac{24\sqrt{10}}{4}
=6\sqrt{10}
$