(4.5-x)(x=0.4)

Solution for (4.5-x)(x=0.4) equation:

(4.5-x)(x=0.4)

We move all terms to the left:

(4.5-x)(x-(0.4))=0

We add all the numbers together, and all the variables

(-1x+4.5)(x-(0.4))=0


We calculate terms in parentheses: +(-1x+4.5)(x-(0.4)), so:

-1x+4.5)(x-(0.4)

We add all the numbers together, and all the variables

-1x+4.5)(x-0.4

Back to the equation:

+(-1x+4.5)(x-0.4)


We multiply parentheses ..

(-1x^2+0.4x+4.5x-1.8)=0

We get rid of parentheses

-1x^2+0.4x+4.5x-1.8=0

We add all the numbers together, and all the variables

-1x^2+4.9x-1.8=0

a = -1; b = 4.9; c = -1.8;
Δ = b2-4ac
Δ = 4.92-4·(-1)·(-1.8)
Δ = 16.81
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{-(4.9)-\sqrt{16.81}}{2*-1}=\frac{-4.9-\sqrt{16.81}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4.9)+\sqrt{16.81}}{2*-1}=\frac{-4.9+\sqrt{16.81}}{-2}
$