Compute
a) lim(x→-1)(x+1)/(x²+1) = ___
b) lim(x→π)(sinx)/(x) = ___
c) lim(x→a)(f(x))/(g(x)) as f(a)=0 and g(a)!=0 can be ___.
d) lim(x→a)(f(x))/(g(x)) as f(a)=0 and g(a)!=0 can be ___.