-3x(3x+15)-(x+10)=35

Solution for -3x(3x+15)-(x+10)=35 equation:

-3x(3x+15)-(x+10)=35

We move all terms to the left:

-3x(3x+15)-(x+10)-(35)=0

We multiply parentheses

-9x^2-45x-(x+10)-35=0

We get rid of parentheses

-9x^2-45x-x-10-35=0

We add all the numbers together, and all the variables

-9x^2-46x-45=0

a = -9; b = -46; c = -45;
Δ = b2-4ac
Δ = -462-4·(-9)·(-45)
Δ = 496
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:

$\sqrt{\Delta}=\sqrt{496}=\sqrt{16*31}=\sqrt{16}*\sqrt{31}=4\sqrt{31}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-46)-4\sqrt{31}}{2*-9}=\frac{46-4\sqrt{31}}{-18}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-46)+4\sqrt{31}}{2*-9}=\frac{46+4\sqrt{31}}{-18}
$