45=-5x(-10+x)

Solution for 45=-5x(-10+x) equation:

45=-5x(-10+x)

We move all terms to the left:

45-(-5x(-10+x))=0

We add all the numbers together, and all the variables

-(-5x(x-10))+45=0


We calculate terms in parentheses: -(-5x(x-10)), so:

-5x(x-10)

We multiply parentheses

-5x^2+50x

Back to the equation:

-(-5x^2+50x)


We get rid of parentheses

5x^2-50x+45=0

a = 5; b = -50; c = +45;
Δ = b2-4ac
Δ = -502-4·5·45
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-50)-40}{2*5}=\frac{10}{10}
=1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-50)+40}{2*5}=\frac{90}{10}
=9
$