We want to simplify:
[tex] (\frac{1}{x+3}+ \frac{6}{ x^{2} +4x+3})* \frac{x+3}{x+1} [/tex]
first we factorize [tex]x^{2} +4x+3[/tex] as [tex](x+3)(x+1)[/tex]
then multiply [tex]\frac{1}{x+3}[/tex] by [tex] \frac{x+1}{x+1} [/tex] to equalize the denominators of the first expression, and add the fractions.
[tex](\frac{1}{x+3}*\frac{x+1}{x+1} + \frac{6}{(x+3)(x+1)})* \frac{x+3}{x+1} [/tex]
[tex]\frac{x+7}{(x+3)(x+1)}* \frac{x+3}{x+1}[/tex]
simplify x+3:
[tex]\frac{x+7}{(x+1)}* \frac{1}{x+1}= \frac{x+7}{ x^{2} +2x+1} [/tex]
a.
[tex]\frac{x+7}{ x^{2} +2x+1}[/tex]
b.
steps already described
c.
x cannot be -1, nor -3 because the fractions with denominators (x+1) and (x+3) would not be defined.