(1) Lets say you have the progression [itex] 5 + 12 + 21 + ... + 1048675 [/itex] and you want to find the sum of 20 terms. I know that the kth term is given by [itex] 2^{k} +3 + 5(k-1) [/itex]. So would I treat the [itex] 2^{k} [/itex] terms separately from the [itex] 3 + 5(k-1) [/itex] terms? Would it be [itex] 2 + 4 + 8 + 16 +... + 2^{n} [/itex] and [itex] 3 + 8 + 13 + ... + (3+5(k-1)) [/itex]. Would the total sum be [itex] \frac{2 - 2(2)^{n}}{-1} + \frac{n}{2}(3+ (3+5(k-1)) [/itex]?(adsbygoogle = window.adsbygoogle || []).push({});

[tex] 2097248 + 1010 [/tex]

(2) [tex] 3 + 10 + 25 + ... + 39394 [/tex] and you want to find sum of first 10 terms. I know that the kth term is [itex] 2 \times 3^{k-1} + 1 + 3(k-1) [/itex] Would i do the same thing and treat the [itex] 3^{k-1} [/itex] and [itex] 1 + 3(k-1) [/itex] separately?

Thanks

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Help with math Progressions

**Physics Forums | Science Articles, Homework Help, Discussion**