## kena 3 years ago Which of the following is the formula for the geometric sequence? 8, -16, 32, -64, ...

1. Outkast3r09

a_1rn

2. guccimayne

can any of you guys help me with my assignment?

3. kena

these are the answers available??? an=-1(3)n − 1 an=1(-3)n − 1 an=3(-1)n − 1 an=3(-3)n − 1

4. Outkast3r09

not sure... i thoght the ratio was -2

5. Outkast3r09

personally i thought the geometric sequence was \[a_1r^n=8(-2)^n\]

6. mubzz

A geometric sequence or a geometric progression is represented by \[a _{n}= ar ^{n-1}\] Where n is the number of the term, a is the first term and r is the common ratio. The first term of a geometric sequence is always a, so in your case, that would be 8 Now you need to find 'r' First term = a = 8 Second term = ar = 8r =-16 Third term = ar^2 = 8r^2 = 32 Divide the second term by the first term and you get r = -2 So the correct answer is =8(−2)^n-1

7. kena

thanks

8. Outkast3r09

that is not an answer -.- though

9. kena

\[solve for x: x-6\div5-4x+4\div5=3\]