Write an explicit formula for the sequence 2,-3,-8,-13,-18 then fin the 13th term

The factorization of 8x3 -125 is (2x-5)(jx2 +kx+25)

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.

David is spreading mulch on a triangular area of his flower bed. the coordinates of the vertices of the area are (1, 3), (9, 3), and (4, 6). what is the area of the triangle if each square has an area of 3 square feet?