X intercept is when y=0
or f(x) = 0
set the f(x)'s to 0
your answer is C
x-1=0 x+1=0 x+3=0
so x= -3, -1, and 1
The points (0, 3) and (4, -1) are on the graph of y = -x + 3.
I have a site that I use a lot that is perfect for problems like these. It's called Desmos.com. It's basically a free online graphing calculator that is super helpful for most problems relating to graphs.