3(x*3)(x+5)=75

Solution for 3(x*3)(x+5)=75 equation:

3(x*3)(x+5)=75

We move all terms to the left:

3(x*3)(x+5)-(75)=0

We add all the numbers together, and all the variables

3(+x*3)(x+5)-75=0

We multiply parentheses ..

3(+3x^2+15x)-75=0

We multiply parentheses

9x^2+45x-75=0

a = 9; b = 45; c = -75;
Δ = b2-4ac
Δ = 452-4·9·(-75)
Δ = 4725
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:

$\sqrt{\Delta}=\sqrt{4725}=\sqrt{225*21}=\sqrt{225}*\sqrt{21}=15\sqrt{21}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(45)-15\sqrt{21}}{2*9}=\frac{-45-15\sqrt{21}}{18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(45)+15\sqrt{21}}{2*9}=\frac{-45+15\sqrt{21}}{18}
$