## Algebra 1: Common Core (15th Edition)

The point-slope form is y=mx+b.The formula for slope is m=$\frac{y2-y1}{x2-x1}$ Using the point from the graph; (-1,1)(1,-1) The slope is m=$\frac{1-(-1)}{-1-1}$=$\frac{2}{-2}$=-1 Using the point-slope formula and (1,-1) and m=-1: $-1=-1(1)+b$ $-1=-1+b$ $0=b$ Plug these values into the point-slope form so the equation is $y=-1x+0$ $y=-x$