## If a + 1, 2a + 1, 4a – 1 are in A.P

If a + 1, 2a + 1, 4a - 1 are in A.P., then the value of a is: A. 1 B. 2 C. 3 D. 4 Answer: Option B…

## If an A.P. has a = 1, tn = 20 and sn = 399..

If an A.P. has a = 1, tn = 20 and sn = 399, then value of n is : A. 20 B. 32 C. 38 D. 40 Answer: Option…

## 15th term of A.P., x – 7, x – 2..

15th term of A.P., x - 7, x - 2, x + 3, ........ is A. x + 63 B. x + 73 C. x + 83 D. x +…

## Which term of the A.P. 24, 21, 18..

Which term of the A.P. 24, 21, 18, ............ is the first negative term? A. 8th B. 9th C. 10th D. 12th Answer: Option C Show Answer Solution(By Apex Team)…

## For A.P. T18 – T8 = …….. ?

For A.P. $\mathrm{T}_{18}-\mathrm{T}_{8}$ = ........ ? A. d B. 10d C. 26d D. 2d Answer: Option B Show Answer Solution(By Apex Team) \begin{aligned}\mathrm{T}_{\mathrm{n}}&=\mathrm{a}+(\mathrm{n}-1)\times\mathrm{d}\\ \mathrm{T}_{18}&=\mathrm{a}+17\mathrm{~d}\\ \mathrm{~T}_8&=\mathrm{a}+7\mathrm{~d}\\ \mathrm{~T}_{18}-\mathrm{T}_8&=17\mathrm{~d}-7\mathrm{~d}\\ &=10\mathrm{~d}\end{aligned}

## For an A.P. if a25 – a20 = 45, then d..

For an A.P. if $\mathbf{a}_{\mathbf{2 5}}-\mathbf{a _ { 2 0 }}$ = 45, then d equals to: A. 9 B. -9 C. 18 D. 23 Answer: Option A Show Answer…