Quiz Discussion

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

The nth term of an A.P., the sum of whose n terms is Sn, is

• 1] Sn + Sn - 1
• 2] Sn - Sn - 1
• 3] Sn + Sn + 1
• 4] Sn - Sn + 1

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

A bacteria gives birth to two new bacteria in each second and the life span of each bacteria is 5 seconds. The process of the reproduction is continuous until the death of the bacteria. initially there is one newly born bacteria at time t = 0, the find the total number of live bacteria just after 10 seconds :

• 1]

  \(\frac{{{3^{10}}}}{2}\)

• 2]

  310 - 210

• 3]

  243 × (35 -1)

• 4]

  310 - 25

• 5]

  None of these

The 2nd and 6th term of an arithmetic progression are 8 and 20 respectively. What is the 20th term?

• 1] 56
• 2] 65
• 3] 59
• 4] 62

If a, b, c are in A.P., then (a – c)²/ (b² – ac) =

• 1]

  3

• 2]

  4

• 3]

  1

• 4]

  2

What is the sum of the first 12 terms of an arithmetic progression if the 3^rd term is -13 and the 6^th term is -4?

• 1]

  -30

• 2]

  41

• 3]

  -23

• 4]

  -34

The first and last term of an A.P. is a and l respectively. If S is the sum of all the terms of the A.P. and the common difference is given by \(\frac{{{l^2} - {a^2}}}{{k - \left( {l + a} \right)}}\)   then k = ?

• 1] S
• 2] 2S
• 3] 3S
• 4] None of these

If the nth term of an A.P. is 2n + 1, then the sum of first n terms of the A.P. is

• 1] n(n - 2)
• 2] n(n + 2)
• 3] n(n + 1)
• 4] n(n - 1)

The 3rd and 9th term of an arithmetic progression are -8 and 10 respectively. What is the 16th term?

• 1] 34
• 2] 28
• 3] 25
• 4] 31