Question 119345
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
It does seem a little ominous.
Break it down into smaller steps. 
First 
{{{b^2}}}
Then 
{{{4*a*c}}}
That's were you have to watch your positive and negative signs.
Then subtract those two. 
{{{b^2-4ac}}}
In mathematics, that term is called the discriminant. 
Let's call it D.
{{{D=b^2-4ac}}}
Take the square root of D and the rest is just addition and division. 
{{{x=(-b +- sqrt(D))/(2*a) }}}
Practice, practice, practice. 
Start with the answer, work backwards, and see where you run into problems. 
{{{(x+5)(x-3) = x*x-3x+5x-3*5}}} 
{{{(x+5)(x-3) = x^2+2x-15}}}
The answers should be x=-5,3. 
{{{(x+5)(x-3) = x^2+2x-15}}}
{{{b^2=4}}}
{{{4ac=4(1)(-15)=-60}}}
{{{D=b^2-4ac=4-(-60)=64}}}
{{{sqrt(D)=sqrt(64)=8}}}
{{{x=(-b +- sqrt(D))/(2*a) }}}
{{{x=(-2 +- 8)/(2*1) }}}
{{{x[1]=(-2 + 8)/(2) }}}
{{{x[1]=(6)/(2) }}}
{{{x[1]=3 }}}
{{{x[2]=(-2 - 8)/(2) }}}
{{{x[2]=(-10)/(2) }}}
{{{x[2]=-5 }}}
If you find you're making mistakes in the same place, pay more attention in that area until you're more comfortable doing it. 
Good luck.