the first and the last term of an ap are 4 and 81 respectively if common difference is 7 find the number term of AP and their sum
Answers
Answered by
1
Answer:
use the formulae an=a+(n-1) ×d an=81a=4d=781=4+(7n-7)81=-3+7n81+3=7n84=7nn=84÷7[tex] \frac{
please follow me
Answered by
0
Answer:
a= 4 an= 81 d = 7
an = a + (n-1) d
81 = 4+(n-1) 7
n-1 = 81-4/7
n-1 = 77/7
n= 11+1=12
Sn= n/2 (a+an)
S12 = 12/2 (3+81)
S12 =6× 84
S12 = 504
Similar questions