0=7x-4x(2x-9)

Solution for 0=7x-4x(2x-9) equation:

0=7x-4x(2x-9)

We move all terms to the left:

0-(7x-4x(2x-9))=0

We add all the numbers together, and all the variables

-(7x-4x(2x-9))=0


We calculate terms in parentheses: -(7x-4x(2x-9)), so:

7x-4x(2x-9)

We multiply parentheses

-8x^2+7x+36x

We add all the numbers together, and all the variables

-8x^2+43x

Back to the equation:

-(-8x^2+43x)


We get rid of parentheses

8x^2-43x=0

a = 8; b = -43; c = 0;
Δ = b2-4ac
Δ = -432-4·8·0
Δ = 1849
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1849}=43$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-43)-43}{2*8}=\frac{0}{16}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-43)+43}{2*8}=\frac{86}{16}
=5+3/8
$