Question

Express the series using sigma notation. 10 + 50 + 250 + 1250.

Answer 1

Each next term is being multiplied by 5. Assuming there are only 4 terms to the sum, you have


`10+50+250+1250=10*5^0+10*5^1+10*5^2+10*5^3=\displaystyle\sum_(i=0)^310*5^i`