3(x-5)x=7.4

Solution for 3(x-5)x=7.4 equation:

3(x-5)x=7.4

We move all terms to the left:

3(x-5)x-(7.4)=0

We add all the numbers together, and all the variables

3(x-5)x-7.4=0

We multiply parentheses

3x^2-15x-7.4=0

a = 3; b = -15; c = -7.4;
Δ = b2-4ac
Δ = -152-4·3·(-7.4)
Δ = 313.8
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{-(-15)-\sqrt{313.8}}{2*3}=\frac{15-\sqrt{313.8}}{6}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+\sqrt{313.8}}{2*3}=\frac{15+\sqrt{313.8}}{6}
$