Recall that the slope-intercept equation of a line is given by the formula y=mx+b where m is the slope and b is the y intercept.
To find the value of b, we simply see the value of the function at x=0. From the graph, we see that whenever x=0 the value of y is -1. This leads to b=-1.
Now, to calculate the slope, we take two points from the line. Let us take the points (0,-1) and (2,0). We proceed as follows:
Recall that given points (a,b) and (c,d) the slope of the line that passes through them is given by the formula
In our case, we take a=0,b=-1, c=2 and d=0, so we get
so we get that the line equation of the graph in slope intercept form is