# Geometric equations with variable terms

• June 4th 2009, 04:58 PM
Unmath Sam
Geometric equations with variable terms
Hello,

I'm not sure if my title is correct terminology but I am stuck. I can work out a geometric progression easily and use the equations. Unfortunately when the equation includes a term that relies on the value of another, I am confused.

What do I do in said situation? Say there are three terms, a + b + c, the value of b is a to a power and c is an exact value.

What sort of steps would I take to work backwards to get the value? (Sleepy)

$GPn = a * ratio^n-1$

Thanks,
Unmath Sam
• June 4th 2009, 06:57 PM
apcalculus
Quote:

Originally Posted by Unmath Sam
Hello,

I'm not sure if my title is correct terminology but I am stuck. I can work out a geometric progression easily and use the equations. Unfortunately when the equation includes a term that relies on the value of another, I am confused.

What do I do in said situation? Say there are three terms, a + b + c, the value of b is a to a power and c is an exact value.

What sort of steps would I take to work backwards to get the value? (Sleepy)

$GPn = a * ratio^n-1$

Thanks,
Unmath Sam

I am not sure I understand your question correctly. Are you referring to recursive forms of sequences? The recursive form of the geometric sequence should be:

a_n = r a_(n-1) where r is the ratio, otherwise it would not be a geometric sequence.

If you would share a specific problem we may be able to help answer your question.

good luck!