3x*5x-4=56

Solution for 3x*5x-4=56 equation:

3x*5x-4=56

We move all terms to the left:

3x*5x-4-(56)=0

We add all the numbers together, and all the variables

3x*5x-60=0

Wy multiply elements

15x^2-60=0

a = 15; b = 0; c = -60;
Δ = b2-4ac
Δ = 02-4·15·(-60)
Δ = 3600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3600}=60$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-60}{2*15}=\frac{-60}{30}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+60}{2*15}=\frac{60}{30}
=2
$