Posted by **kazz** on Friday, January 4, 2013 at 2:19pm.

The first three terms of the sequence -8,x,y,72... form an arithmetic sequence, while the second, third and fourth terms form a geometric sequence. Determine x and y.

- SeQuEnCeS and SeRiEs: HELP PLZ! -
**Steve**, Friday, January 4, 2013 at 2:28pm
y-x = x+8

y/x = 72/y

y = 2x+8

(2x+8)/x = 72/(2x+8)

4x^2+32x+64 = 72x

4x^2-40x+64 = 0

x^2 - 10x + 16 = 0

(x-2)(x-8) = 0

x=2,8

y=12,24

so, we have

-8,2,12,72

or

-8,8,24,72

- SeQuEnCeS and SeRiEs: HELP PLZ! -
**kazz**, Friday, January 4, 2013 at 2:33pm
thanks:-)

## Answer This Question

## Related Questions

- math - in an arithmetic sequence the common difference is equal to 2.the first ...
- Maths - The first, third and ninth terms of an arithmetic sequence form the ...
- Maths - 1..The first 2 terms of a geometric progression are the same as the ...
- math - in an arithmetic sequence whose first term is 4, the 1st, 3rd and 7th ...
- Maths - An arithmetic and a geometric sequence have the same first terms.(2).......
- Algebra - Determine whether each sequence is arithmetic or geometric. Find the ...
- Math Help!!! - determine whether each sequence is arithmetic or geometric. find ...
- math - Determine whether each sequence is arithmetic or geometric. Find the next...
- math... - how can I tell if a sequences is airthmetic, geometric or neither? ...
- Can someone help me?! - The 1st, 5th and 13th terms of an arithmetic sequence ...

More Related Questions