Quiz Discussion

Find the first term of an AP whose 8th and 12th terms are respectively 39 and 59.

• 1] 5
• 2] 6
• 3] 4
• 4] 3
• 5] 7

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)

If Sn denote the sum of the first n terms of an A.P. If S2n = 3Sn , then S3n : Sn is equal to

• 1] 4
• 2] 6
• 3] 8
• 4] 10

If four numbers in A.P. are such that their sum is 50 and the greatest number is 4 times the least, then the numbers are

• 1] 5, 10, 15, 20
• 2] 4, 10, 16, 22
• 3] 3, 7, 11, 15
• 4] None of these

What is the sum of the first 12 terms of an arithmetic progression if the first term is -19 and last term is 36?

• 1] 192
• 2] 230
• 3] 102
• 4] 214

Two A.P.’s have the same common difference. The first term of one of these is 8 and that of the other is 3. The difference between their 30th terms is

• 1] 11
• 2] 3
• 3] 8
• 4] 5

Sum of n terms of the series \(\sqrt 2   +   \sqrt 8   +   \sqrt {18}   +   \sqrt {32}   +  \) ....... is

• 1]

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

• 2]

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

• 3]

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

• 4]

  1

15th term of A.P., x - 7, x - 2, x + 3, ........ is

• 1] x + 63
• 2] x + 73
• 3] x + 83
• 4] x + 53

The 3rd and 7th term of an arithmetic progression are -9 and 11 respectively. What is the 15th term?

• 1] 28
• 2] 87
• 3] 51
• 4] 17