Let <em>f(x)</em> be the sum of the geometric series,
for |<em>x</em>| < 1. Then taking the derivative gives the desired sum,
X = 3.5.....this is a vertical line that never crosses the y axis. It crosses the x axis at 3.5......so the x int is : (3.5,0)
y = -6.5...this is a horizontal line which never crosses the x axis. It crosses the y axis at -6.5....so the y int is (0,-6.5)