What are the first four terms of the geometric sequence with a t1 = 3 and tn = 2tn-1?

The sixth grade art students are making a mosaic using tiles in the shape of right triangles.each tile has leg measures of 3 centimeters and 5 centimeters.i f there are 200 tiles in the mosaic what is the area of the mosaic.

One of the same side angles of two parallel lines is 20° smaller than the other one. find the measures of these two angles.

Which function has the domain x> -11?