10=5x^2+30x-15

Solution for 10=5x^2+30x-15 equation:

10=5x^2+30x-15

We move all terms to the left:

10-(5x^2+30x-15)=0

We get rid of parentheses

-5x^2-30x+15+10=0

We add all the numbers together, and all the variables

-5x^2-30x+25=0

a = -5; b = -30; c = +25;
Δ = b2-4ac
Δ = -302-4·(-5)·25
Δ = 1400
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:

$\sqrt{\Delta}=\sqrt{1400}=\sqrt{100*14}=\sqrt{100}*\sqrt{14}=10\sqrt{14}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-30)-10\sqrt{14}}{2*-5}=\frac{30-10\sqrt{14}}{-10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+10\sqrt{14}}{2*-5}=\frac{30+10\sqrt{14}}{-10}
$