Is the sequence arithmetic? If so, identify the common difference. 11, 15, 19, 23, ...
1 answer:
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Again, a spreadsheet or suitable calculator makes this short work.
The sum is 184.
_____
The terms being summed are ...
2·3² +3 = 2·9 +3 = 18 +3 = 21
2·4² +3 = 35
2·5² +3 = 53
2·6² +3 = 75
Their total is
21 +35 +53 +75 = 184
The sum is 184.
_____
The terms being summed are ...
2·3² +3 = 2·9 +3 = 18 +3 = 21
2·4² +3 = 35
2·5² +3 = 53
2·6² +3 = 75
Their total is
21 +35 +53 +75 = 184