Why we calculate the nature of denominator before find out asymptotes? like to fimd out aymptote of (2x/(x+1)) first we dicuss whereb X tends to +or-(infin) and as X tends to -1

X=-1 is the asymptote of this function.
We find out that X tends to -1 from right hand side or left to know how to plot the function.
If x tends to -1 from right, it would mean the function is +infinity.

x=-1 is the assymptote of the given eq we first check denominator because asymptotes are tangents at infinity so when the denominator tends to zero at that pt tangents are called asymptotes