28=x(3x-5)

Solution for 28=x(3x-5) equation:

28=x(3x-5)

We move all terms to the left:

28-(x(3x-5))=0


We calculate terms in parentheses: -(x(3x-5)), so:

x(3x-5)

We multiply parentheses

3x^2-5x

Back to the equation:

-(3x^2-5x)


We get rid of parentheses

-3x^2+5x+28=0

a = -3; b = 5; c = +28;
Δ = b2-4ac
Δ = 52-4·(-3)·28
Δ = 361
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{361}=19$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-19}{2*-3}=\frac{-24}{-6}
=+4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+19}{2*-3}=\frac{14}{-6}
=-2+1/3
$