Which is equivalent to the following expression? (2x^2+4xy-y^2)+(x^2+3xy-y^2) a. 3x^2-7xy-2y^2 b. 3x^2+7xy+2y^2 c. 3x^2+7xy-2y^2 d. 3x^2-7xy+2y^2

A3-dimensional figure has a square base and 4 lateral faces that meet at a point. explain the difference between the cross sections when a slice is made perpendicular to the base through the vertex, and when a slice is made perpendicular to the base and not through the vertex