Mathematics

Problem

State the first term

u_1

and common ratio

r

for these geometric sequences: (a) 5, 15, 45, 135, ... (b) 72, 36, 18, 9, ... (c) 2, -8, 32, -128, ... (d) 6, -2,

\frac{2}{3}

-\frac{2}{9}

, ...