Question

Find the 16th term of the AP 7,11,15,19. find the sum of first six​

Answer 1

Answer:

7 11 15 19 23 27 31 35 39 43 47 51 55 59

67 is the 16 term

103 is the sum of 1st 6 terms

Answer 2

solution

the ap series is

7,11,15,19,......

now first term(a)=7

difference (d)=11-7=4

now.....the 16th term is

a(16)=a+(16-1)d=7+15(4)=67

now the sum of first six terms is

$s(6) = \frac{6(2a + (6 - 1)d)}{2} \\ \: \: \: \: \: \: \: \: \: = 3(2 \times 7 + 5 \times 4) \\ \: \: \: \: \: \: \: \: \: = 3 \times 34 = 102$

hope this helps you...