Question

Q1. Find the 6th and 15th terms of the A.P whose first term is 6 and common difference is 7. Q2. The 12th term of an A.P is -41 given the first term is 3, find the 20th term. Q3. If 8, A, B, C, D, 38, 44, 50, Find the values of A, B, C, AND D Q4. How many terms has an A.P. whose common difference and first term are -6 and 8 respectively and the last term is -82. .... ​

Answer 1

Explanation:

1.

nth term of an AP is a1 + d(n - 1)

6th term = 6 + 7(6 - 1)

= 6 + 35

= 41.

15th term

= 6 + 7(15-1)

= 6 + 98

= 104.

2.

12th term :

3 + d(12-1) = -41

11d = -44

d =-4

So,

20th term = 3 + -4* 19

= -73

3.

8 A B C D 38 44 50

d = (38 - 8) / 5

= 6

So, A B C D = 14, 20 , 26 32.

4.

a1 = 8 and d = -6

8 - 6(n - 1) = -82

8 - 6n + 6 = -82

-6n = -96

n = 16

It has 16 terms.