Quiz Discussion

(1) + (1 + 1) + (1 + 1 + 1) + ....... + (1 + 1 + 1 + ...... n - 1 times) = ......

• 1]

  \(\frac{{n\left( {n + 1} \right)}}{2}\)

• 2]

  \(\frac{{n\left( {n - 1} \right)}}{2}\)

• 3]

  \({n^2}\)

• 4]

  n

Which term of the A.P. 24, 21, 18, ............ is the first negative term?

• 1] 8th
• 2] 9th
• 3] 10th
• 4] 12th

The 3rd and 6th term of an arithmetic progression are 13 and -5 respectively. What is the 11th term?

• 1] -29
• 2] -41
• 3] -47
• 4] -35

The sum of first n odd natural numbers in

• 1] 2n - 1
• 2] 2n + 1
• 3] n2
• 4] n2 - 1

Consider an infinite G.P. with first term a and common ratio r, its sum is 4 and the second term is 3/4, then

• 1]

  a = 7/4, r = 3/7

• 2]

  a = 2, r = 3/8

• 3]

  a = 3, r = 1/4

• 4]

  a = 3/2, r = ½

If a + 1, 2a + 1, 4a - 1 are in A.P., then the value of a is:

• 1] 1
• 2] 2
• 3] 3
• 4] 4

If log 2, log (2^x -1) and log (2^x + 3) are in A.P, then x is equal to ___

• 1]

   

  5/2

• 2]

  log₂5

• 3]

  log₃2

• 4]

   

  3/2

For an A.P. if a25 - a20 = 45, then d equals to:

• 1] 9
• 2] -9
• 3] 18
• 4] 23

In an A.P., if d = -4, n = 7, a_n = 4, then a is

• 1]

  6

• 2]

  7

• 3]

  20

• 4]

  28

Find the 15th term of the sequence 20, 15, 10 . . . . .

• 1] -45
• 2] -55
• 3] -50
• 4] 0