math
posted by bluebabe on .
if you evaluate the expression 5a2 for a=1,2,3,4 and so on,you form a sequence of numbers.what is the sum of the first 10 numbers in the sequence you form by evaluating the expression for a=1 through 10? explain your reasoning

you will get the numbers
3, 8, 13, ... 48 for 10 terms
This is an arithmetic sequence where a = 3, d = 5 and n = 10
Sum(10) = (10/2)(first + last)
= 5(3+48) = 255