The 1st and 2nd terms of a geometric progression are 4 and 12.

Find the sum of the first 10 terms.

The 3rd and 4th terms of a geometric progression are 5 and -20.

Find the 1st term, the common ratio, and the 9th term.

Enter your answer as: \(a,r,u_9\) (comma-separated).

The 4th and 6th terms of a geometric progression are 200 and 800.

Find two possible values of the common ratio and the corresponding 1st terms.

Enter your answer as: \(r_1,a1,r_2,a2\) (comma-separated), with \(r_1\) positive.

Find the 13th term of the geometric progression

\(1.1,\ 1.21,\ 1.331,\ldots\)

Give your answer correct to 3 significant figures.

Find the sum of the first 11 terms of the geometric progression

\(\frac12-\frac14+\frac18-\frac1{16}+\cdots\)

Give your answer as a fraction in simplest form.