Question 318480
TO make things clearer, be sure to use parentheses especially in denominators of complex fractions. 
I think this is the expression you're trying to simplify.
{{{x+1/(x^2-4) + x/(3x+6)}}}
When adding/subtracting with fractions, you need a common denominator. 
In this case, the first expression has a denominator of {{{1}}}.
Second expression: {{{x^2-4=(x+2)(x-2)}}}
Third expression:{{{3x+6=3(x+2)}}}
So a common denominator would be {{{(x+2)(x-2)}}}.
{{{x+1/(x^2-4) + x/(3x+6)= x*(((x+2)(x-2))/((x+2)(x-2)))+1/((x+2)(x-2)) + (1/3)*(x(x-2))/((x+2)(x-2))}}}
{{{x+1/(x^2-4) + x/(3x+6)=(3/3)*(x*(x^2-4)+(3/3)+(1/3)*(x(x-2)))/((x+2)(x-2))}}}
{{{x+1/(x^2-4) + x/(3x+6)=(3x*(x^2-4)+3+(x(x-2)))/(3(x+2)(x-2))}}}
{{{x+1/(x^2-4) + x/(3x+6)=((3x^3-12x)+3+(x^2-2x))/(3(x+2)(x-2))}}}
{{{highlight(x+1/(x^2-4) + x/(3x+6)=(3x^3+x^2-14x+3)/(3(x+2)(x-2)))}}}