13=(3+5x-2)(-2x+5)

Solution for 13=(3+5x-2)(-2x+5) equation:

13=(3+5x-2)(-2x+5)

We move all terms to the left:

13-((3+5x-2)(-2x+5))=0

We add all the numbers together, and all the variables

-((5x+1)(-2x+5))+13=0

We multiply parentheses ..

-((-10x^2+25x-2x+5))+13=0


We calculate terms in parentheses: -((-10x^2+25x-2x+5)), so:

(-10x^2+25x-2x+5)

We get rid of parentheses

-10x^2+25x-2x+5

We add all the numbers together, and all the variables

-10x^2+23x+5

Back to the equation:

-(-10x^2+23x+5)


We get rid of parentheses

10x^2-23x-5+13=0

We add all the numbers together, and all the variables

10x^2-23x+8=0

a = 10; b = -23; c = +8;
Δ = b2-4ac
Δ = -232-4·10·8
Δ = 209
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{-(-23)-\sqrt{209}}{2*10}=\frac{23-\sqrt{209}}{20}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-23)+\sqrt{209}}{2*10}=\frac{23+\sqrt{209}}{20}
$