Question 19 & 20
Question: Write missed terms in the sequence 1,2,6,12,20,21,…………..,47,56? FPSC AD IB 2017 -2nd batch
Solution: Here in general counting starting 1,2,3,4,5,…….. each number is multiplied by its next number;
1 is multiplied by 2 then comes first term i-e 2
2 is multiplied by 3 then comes second term i-e 6
3 is multiplied by 4 then comes third term i-e 12
4 is multiplied by 5 then comes fourth term i-e 20
5 is multiplied by 6 then comes fifth term i-e 30
……………………………………………………….
and so on !!!
Question 20: The numbers are -1, 2, and 2/3. Which one is irrational ?
Solution:
Irrational numbers are those numbers in which division process never completes i-e in the answer the digits after point never end
So here we see the division never ends and digits after ‘.’ never ends i-e 6666666666666666……………….. goes on
so
is a irrational number