Which equation results from adding the equations in this system?
-2x+y = 8
5x-y=-5
7x= 13
7x= 3
3x - 3
3x - 13

Find the measure of the interior angles of the following regular polygons: a triangle, a quadrilateral, a pentagon, an octagon, a decagon, a 30-gon, a 50-gon, and a 100-gon.

Sketch one cycle if the cosine function y=2cos2theta

Let f(x) = 3 − x . find the average rate of change of f(x) from x = a to x = a + h and simplify your answer so that no single factor of h is left in the denominator.