math geometric sequences?

1 ⤊

i need help with my homework. can someone help me.

here is the question:
t4 = 3, t8 = 243 - Find t11

Can you show your work too. thanks

2007-10-23 12:18:37 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics

Each term in the sequence = 3 times the term before it.

t4 = 3
t5 = 9
t6 = 27
t7 = 81
t8 = 243
t9 = 729
t10 = 2187
t11 = 6561

2007-10-23 12:22:57 · answer #1 · answered by mathguru 3 · 1⤊ 0⤋

t0 = a, tn = ar^(n-1), so
arÂ³ = 3, ar^7 = 243. then
ar^7 / arÂ³ = r^4 = 243/3 = 81, so r = 3.
That makes t11 = t8(3Â³) = 243(27) = 6561.

2007-10-23 19:24:38 · answer #2 · answered by Philo 7 · 0⤊ 0⤋

t8/t4 = 243/3 = 81 = 3^4

t11 = 243*(3^3)

2007-10-23 19:23:02 · answer #3 · answered by fcas80 7 · 0⤊ 0⤋