Expand the geometric series. Enter your answers separated by commas, with no spaces. 3"-1

The fourth term is 12 and the seventh term is 32 Find the first and nth terms..

Ryan is building a triangle sequence so that one triangle is added to the right each time, as shown below. How many matchsticks will he use for the nth figure and for the figure one before the nth? Click the icon to view the matchstick square figures. The nth figure will take matchsticks to build. (Type an expression using n as the variable. Simplify your answer.) The figure one before the nth figure will take matchsticks to build. (Type an expression using n as the variable. Simplify your answer.)