3x(5x+2)=35

Solution for 3x(5x+2)=35 equation:

3x(5x+2)=35

We move all terms to the left:

3x(5x+2)-(35)=0

We multiply parentheses

15x^2+6x-35=0

a = 15; b = 6; c = -35;
Δ = b2-4ac
Δ = 62-4·15·(-35)
Δ = 2136
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:

$\sqrt{\Delta}=\sqrt{2136}=\sqrt{4*534}=\sqrt{4}*\sqrt{534}=2\sqrt{534}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(6)-2\sqrt{534}}{2*15}=\frac{-6-2\sqrt{534}}{30}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+2\sqrt{534}}{2*15}=\frac{-6+2\sqrt{534}}{30}
$