The 4th term of an Ap is 6. if the sum of the 8th and 9th terms is -72,find the common difference

Answer 1

t(4) = 6 ---- a + 3d = 6

t(8) + t(9) = -72
a+7d + a+8d = -72
2a + 15d = -72
double the first equation
2a + 6d = 12
subtract them
9d = -84
d = -84/9 = -28/3

Answer 2

Please how did you get -28/3

Answer 3

The first and last terms of an arithmetic progression are 1 and 121 respectively. Find
1.the number of terms in arithmetic progression
2.the common difference between them if d sum of its terms is
(a) 549. (b) 671. (c) 976.
(d) 1281

Answer 4

Plz can i get d solving of dis question

Answer 5

You are right thanks Alot

Answer 6

You are doing well

Answer 7

This answer isn't correct

Answer 8

the first winner lottery get #2000 while subsequently winners get #50 less than the proceeding winner how much will the winner the 20th position get

Answer 9

91/3