Determine a when : a+a*1.2+a*(1.2)^2+a*(1.2)^2+a*(1.2)^3+...+a*(1.2)^ 24=2000
It's under mixed exercises in my book. But i can't find anything that looks like this in my book. I just can't find out what to do, so ended up trying to guess a and slove it. Anyone can give me a hint. I know it's probarbly very easy...
Matt Westwood identitied the equation: the sum of a geometric sequence.
The first term is:
The common ratio is:
And there are: terms.
The sum of the first terms of a geometric sequence
. . is given by: .
So we have: .
. . Solve for
Well yes okay, but my technique doesn't require you to learn a formula to plug numbers into, it teaches you why the formula works. Still, if it's just a formula for doing your maths homework you want, rather than understanding of why, then no worries.