Could someone please explain how to answer these tricky questions:
1) Which term of the series 8 - 4 + 2 - .... is equal to 1/128 ?
2) Which term of the series 3 + 21 + 147 + .... is equal to 352,947 ?
3) Which term of 7/9 + 14/45 + 28/225 + ... is equal to 224/28,125 ?
4) The third term of a geometric series is 2/5 and the 5th term is 1r 3/5. Find the common ratio and the first term,
5) Find the first term of the series 2/7 + 6/7 + 2r 4/7 + ... that is greater than 100.
The 1st question my teacher couldn't even explain..
Answers:
1) 11th
2) 7th
3) 6th
4) a = 1/10, r = +- 2
5) 208r 2/7 (7th term)
Just need explainations thanks.
1) Which term of the series 8 - 4 + 2 - .... is equal to 1/128 ?
2) Which term of the series 3 + 21 + 147 + .... is equal to 352,947 ?
3) Which term of 7/9 + 14/45 + 28/225 + ... is equal to 224/28,125 ?
4) The third term of a geometric series is 2/5 and the 5th term is 1r 3/5. Find the common ratio and the first term,
5) Find the first term of the series 2/7 + 6/7 + 2r 4/7 + ... that is greater than 100.
The 1st question my teacher couldn't even explain..
Answers:
1) 11th
2) 7th
3) 6th
4) a = 1/10, r = +- 2
5) 208r 2/7 (7th term)
Just need explainations thanks.