5-2x(x=4)

Solution for 5-2x(x=4) equation:

5-2x(x=4)

We move all terms to the left:

5-2x(x-(4))=0

We multiply parentheses

-2x^2+8x+5=0

a = -2; b = 8; c = +5;
Δ = b2-4ac
Δ = 82-4·(-2)·5
Δ = 104
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{104}=\sqrt{4*26}=\sqrt{4}*\sqrt{26}=2\sqrt{26}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-2\sqrt{26}}{2*-2}=\frac{-8-2\sqrt{26}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+2\sqrt{26}}{2*-2}=\frac{-8+2\sqrt{26}}{-4}
$