4=2.8x(x/4)

Solution for 4=2.8x(x/4) equation:

4=2.8x(x/4)

We move all terms to the left:

4-(2.8x(x/4))=0

We add all the numbers together, and all the variables

-(2.8x(+x/4))+4=0

We multiply all the terms by the denominator


-(2.8x(+x+4*4))=0


We calculate terms in parentheses: -(2.8x(+x+4*4)), so:

2.8x(+x+4*4)

We add all the numbers together, and all the variables

2.8x(x+16)

We multiply parentheses

2x^2+32x

Back to the equation:

-(2x^2+32x)


We get rid of parentheses

-2x^2-32x=0

a = -2; b = -32; c = 0;
Δ = b2-4ac
Δ = -322-4·(-2)·0
Δ = 1024
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1024}=32$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-32)-32}{2*-2}=\frac{0}{-4}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-32)+32}{2*-2}=\frac{64}{-4}
=-16
$