In the sequence of numbers 4,7,-7,....., the first term is 4. Each even numbered term is 3 more than the previous term.Each odd numbered term after the first is -1 times the previous term. What is the sum of the first 22 terms?
Answer is 11. The series follows like this: 4, 7 , -7, -4, 4, 7, -7, -4, 4, 7, -7, ..... All terms get cancelled other than 4 & 7. So 4+7=11.
