350(x)=-0.003x^2+1.2x+3.9

Solution for 350(x)=-0.003x^2+1.2x+3.9 equation:

350(x)=-0.003x^2+1.2x+3.9

We move all terms to the left:

350(x)-(-0.003x^2+1.2x+3.9)=0

We get rid of parentheses

0.003x^2-1.2x+350x-3.9=0

We add all the numbers together, and all the variables

0.003x^2+348.8x-3.9=0

a = 0.003; b = 348.8; c = -3.9;
Δ = b2-4ac
Δ = 348.82-4·0.003·(-3.9)
Δ = 121661.4868
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{-(348.8)-\sqrt{121661.4868}}{2*0.003}=\frac{-348.8-\sqrt{121661.4868}}{0.006}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(348.8)+\sqrt{121661.4868}}{2*0.003}=\frac{-348.8+\sqrt{121661.4868}}{0.006}
$