The given equation, y=4x, has the "slope-intercept" form of the equation of a straight line, y=mx+b, where m is the slope and b is the y-intercept. If y=4x, then b is zero, and thus the line goes through the origin. This automatically eliminates 2 of the 4 possible answers. Which ones?
Next: "slope" is often refered to as "rise/run." Which of the remaining two graphs shows a slope of 4/1 (run=1, rise=4)?
