Linear function
Example: y=–2x+4. The slope is m= –2 and the y-intercept is b=4 or the point (0,4). Substituting y=0 and solving for x, we get 0=–2x+4 or x=2. So x=2 is the root of this linear function and the point (2,0) is the x-intercept.  Since the slope is m = –2, the line is decreasing. Since |–2|=2>1, the decrease is relatively steep. For each change in х of 1 (to the right), the value of у changes -2 (goes down).