0=-0.2(x+22)(x-15)

Solution for 0=-0.2(x+22)(x-15) equation:

0=-0.2(x+22)(x-15)

We move all terms to the left:

0-(-0.2(x+22)(x-15))=0

We add all the numbers together, and all the variables

-(-0.2(x+22)(x-15))=0

We multiply parentheses ..

-(-0.2(+x^2-15x+22x-330))=0


We calculate terms in parentheses: -(-0.2(+x^2-15x+22x-330)), so:

-0.2(+x^2-15x+22x-330)

We multiply parentheses

-0.2x^2+3x-4.4x+66

We add all the numbers together, and all the variables

-0.2x^2-1.4x+66

Back to the equation:

-(-0.2x^2-1.4x+66)


We get rid of parentheses

0.2x^2+1.4x-66=0

a = 0.2; b = 1.4; c = -66;
Δ = b2-4ac
Δ = 1.42-4·0.2·(-66)
Δ = 54.76
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{-(1.4)-\sqrt{54.76}}{2*0.2}=\frac{-1.4-\sqrt{54.76}}{0.4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.4)+\sqrt{54.76}}{2*0.2}=\frac{-1.4+\sqrt{54.76}}{0.4}
$