7x-(8x(5x-30))=12

Solution for 7x-(8x(5x-30))=12 equation:

7x-(8x(5x-30))=12

We move all terms to the left:

7x-(8x(5x-30))-(12)=0


We calculate terms in parentheses: -(8x(5x-30)), so:

8x(5x-30)

We multiply parentheses

40x^2-240x

Back to the equation:

-(40x^2-240x)


We get rid of parentheses

-40x^2+7x+240x-12=0

We add all the numbers together, and all the variables

-40x^2+247x-12=0

a = -40; b = 247; c = -12;
Δ = b2-4ac
Δ = 2472-4·(-40)·(-12)
Δ = 59089
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{-(247)-\sqrt{59089}}{2*-40}=\frac{-247-\sqrt{59089}}{-80}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(247)+\sqrt{59089}}{2*-40}=\frac{-247+\sqrt{59089}}{-80}
$