4x*5x=4*5

Solution for 4x*5x=4*5 equation:

4x*5x=4*5

We move all terms to the left:

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

We add all the numbers together, and all the variables

4x*5x-20=0

Wy multiply elements

20x^2-20=0

a = 20; b = 0; c = -20;
Δ = b2-4ac
Δ = 02-4·20·(-20)
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-40}{2*20}=\frac{-40}{40}
=-1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+40}{2*20}=\frac{40}{40}
=1
$