X*5x=210

Solution for X*5x=210 equation:

X*5X=210

We move all terms to the left:

X*5X-(210)=0

Wy multiply elements

5X^2-210=0

a = 5; b = 0; c = -210;
Δ = b2-4ac
Δ = 02-4·5·(-210)
Δ = 4200
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:

$\sqrt{\Delta}=\sqrt{4200}=\sqrt{100*42}=\sqrt{100}*\sqrt{42}=10\sqrt{42}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-10\sqrt{42}}{2*5}=\frac{0-10\sqrt{42}}{10}
=-\frac{10\sqrt{42}}{10}
=-\sqrt{42}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+10\sqrt{42}}{2*5}=\frac{0+10\sqrt{42}}{10}
=\frac{10\sqrt{42}}{10}
=\sqrt{42}
$