Will fan and Medal.
Find the 8th term of the geometric sequence.
1, -2, 4, -8,

Question

Will fan and Medal.
Find the 8th term of the geometric sequence.
1, -2, 4, -8,

solomonzelman · Answer

what pattern do you notice here?

anonymous · Answer

It's going back from positive to negative. But the middle numbers its jumping up and down each time.

solomonzelman · Answer

you are multiplying times -2 each time, right?

solomonzelman · Answer

so, starting from the 1st term, you need to multiply times -2 once to get to the second term.

anonymous · Answer

And you'd keep going from there correct?

solomonzelman · Answer

and starting from 1st term, you need to multiply times -2, 2 times , to find the 3rd term

solomonzelman · Answer

and starting from the 1st term, you need to multiply times -2, 3 times, to find the 4th term

solomonzelman · Answer

this way, you need to multiply times -2, 'n-1' number of times, to find the nth term.

solomonzelman · Answer

and so, you need to multiply times -2, 7 times to find the 8th term

anonymous · Answer

Oh, I see what you are doing there.

solomonzelman · Answer

$1\times (-2)^7=a_8$

solomonzelman · Answer

see why this is the 8th term?

solomonzelman · Answer

(and all you need to do is to calculate that)
I got to go, apologize, and you welcome.

anonymous · Answer

Yes, I understand now. I was confused but I think you gave me a very easy way how to solve it. Thank you!