Y=sinx+ 2cosx + 3, cái này làm sao nhỉ

Which expression is equivalent to (3^2)^-2 a.-81 b.-12 c.1/81 d.1/12

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.

Whit h equation best represents this situation the number 98 increased by an unknown number equal to 120