It's me again, sorry about asking another question, but I couldn't find the formulae anywhere, so heere's the question: Find the first term in the Geometric Progression: 5,10,20, ...... that exceeds 500.
I know that a=5 and r=2. How would I go by working this out? Thanks in advance for your help!
+33616 The n'th term is given by a*rn-1 so you want n such that 5*2n-1 is just greater than 500.
The numbers are small enough to see that if n = 7, then 5*26 = 5*64 is less than 500 and if n = 8 then 5*27 = 5*128 is greater than 500 so the eighth term is the first one greater than 500 and is 5*128 = 640
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+33616 The n'th term is given by a*rn-1 so you want n such that 5*2n-1 is just greater than 500.
The numbers are small enough to see that if n = 7, then 5*26 = 5*64 is less than 500 and if n = 8 then 5*27 = 5*128 is greater than 500 so the eighth term is the first one greater than 500 and is 5*128 = 640
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