Question

the 9th term of arithmatic progression is -32and the sum of 11th and 13th term is -94.Find the common difference

Answer 1

let first term be A and common difference be D
so its 9th term
=A+D(9-1)
=A+8D -------eqaution 1
= -32
now we have
11th term +13th term
=A+D (11-1) +A+D (13-1)
=2A+10D+12D
=2A+22D
= -94
'''A+11D= -47 ------- equa.2
now subtract eq.2 and eq.1
then u get
3D= -15
D= -5

Answer 2

Answer:

-5

Step-by-step explanation:

9th term = a+(9-1)d = a+8d = -32--(2)

11th term = a+(11-1)d = a+10d

13th term = a+(13-1)d = a+12d

a+10d+a+12d=-94

2a+22d=-94

a+11d=-47---(1)

(2)-(1):

-3d=15

d=-5

the common difference is equal to -5