Identify the 12th term of a geometric sequence where a1 = 8 and a6 = –8,192.

Question

anonymous · Answer

a6 = a1*r^5
-8192 = 8*r^5
r^5 = -1024
r = -2
so a12 = a1*r^11 = 8*(-2)^11 = -16384 i guess

anonymous · Answer

ahhhh, that not in my choice of answerss:(

anonymous · Answer

ahh I see now I got dizzy again lol it's too late here
r = -4

anonymous · Answer

so a12 = 8*(-4)^11
sorry for many mistakes lol

anonymous · Answer

ahh, thats not good!:(

anonymous · Answer

but be sorry you have no idea how helpful you are(:

anonymous · Answer

yess thats right!

anonymous · Answer

what about Identify the 17th term of a geometric sequence where a1 = 16 and a5 = 150.06. Round the common ratio and 17th term to the nearest hundredth.

anonymous · Answer

a5 = a1*r^4 
150.6 = 16*r^4
so u can figure r by using calculator 

17th term to the nearest hundredth??
I don't understand my eng is not good enough lol

anonymous · Answer

haha ummm dont worry about that part? so like  Identify the 17th term of a geometric sequence where a1 = 16 and a5 = 150.06. Round the common ratio and 17th term

campbell_st · Answer

stephanizer you need to evaluate the answer for your 1st term

$$T _{12} = 8\times(-4)^{11}$$

as the maths is correct.

anonymous · Answer

ok r^4 is approximately 6.4
so a17 = a1*r^16 = a1*((r^4))^4 = 8*(6.4)^4=.....

anonymous · Answer

but I want to understand eng too lol

anonymous · Answer

no no r is approximately 9.4 lol

campbell_st · Answer

I got $$150.6 = 16r^4$$

r = 1.75

then $$T _{17} = 16 \times(1.75)^{16} =123802$$

anonymous · Answer

^^ how you figure r out ?? did you use calculator??

campbell_st · Answer

$$r^4 = \frac{150.6}{16}$$

then 

$$r = \sqrt[4]{9.4125} = 1.7499$$