0.8/0.2=x2/9

Solution for 0.8/0.2=x2/9 equation:

0.8/0.2=x2/9

We move all terms to the left:

0.8/0.2-(x2/9)=0

We add all the numbers together, and all the variables

-(+x2/9)+0.8/0.2=0

We add all the numbers together, and all the variables

-(+x2/9)+4=0

We get rid of parentheses

-x2/9+4=0

We multiply all the terms by the denominator


-x2+4*9=0

We add all the numbers together, and all the variables

-1x^2+36=0

a = -1; b = 0; c = +36;
Δ = b2-4ac
Δ = 02-4·(-1)·36
Δ = 144
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{144}=12$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-12}{2*-1}=\frac{-12}{-2}
=+6
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+12}{2*-1}=\frac{12}{-2}
=-6
$