Answer
(a) See graph.
(b) domain $(-\infty,\infty)$ range $[-4,\infty)$.
(c) increasing on $(-1,\infty)$, decreasing on $(-\infty,-1)$.
Work Step by Step
(a) Given $f(x)=x^2+2x-3=(x+1)^2-4=(x+3)(x-1)$, we can determining the graph opens up, vertex $(-1,-4)$, axis of symmetry $x=-1$, y-intercept (let x=0) $y=-3$, x-intercepts (f(x)=0) $x=-3,1$. See graph.
(b) We can determine the domain $(-\infty,\infty)$ range $[-4,\infty)$.
(c) We can determine the function is increasing on $(-1,\infty)$, decreasing on $(-\infty,-1)$.
