0.0138=(0.15+x)(x)

Solution for 0.0138=(0.15+x)(x) equation:

0.0138=(0.15+x)(x)

We move all terms to the left:

0.0138-((0.15+x)(x))=0

We add all the numbers together, and all the variables

-((x+0.15)x)+0.0138=0


We calculate terms in parentheses: -((x+0.15)x), so:

(x+0.15)x

We multiply parentheses

x^2+0.15x

Back to the equation:

-(x^2+0.15x)


We get rid of parentheses

-x^2-0.15x+0.0138=0

We add all the numbers together, and all the variables

-1x^2-0.15x+0.0138=0

a = -1; b = -0.15; c = +0.0138;
Δ = b2-4ac
Δ = -0.152-4·(-1)·0.0138
Δ = 0.0777
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-0.15)-\sqrt{0.0777}}{2*-1}=\frac{0.15-\sqrt{0.0777}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.15)+\sqrt{0.0777}}{2*-1}=\frac{0.15+\sqrt{0.0777}}{-2}
$