525=5x(4x+1)

Solution for 525=5x(4x+1) equation:

525=5x(4x+1)

We move all terms to the left:

525-(5x(4x+1))=0


We calculate terms in parentheses: -(5x(4x+1)), so:

5x(4x+1)

We multiply parentheses

20x^2+5x

Back to the equation:

-(20x^2+5x)


We get rid of parentheses

-20x^2-5x+525=0

a = -20; b = -5; c = +525;
Δ = b2-4ac
Δ = -52-4·(-20)·525
Δ = 42025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{42025}=205$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-205}{2*-20}=\frac{-200}{-40}
=+5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+205}{2*-20}=\frac{210}{-40}
=-5+1/4
$