Question

The ninth term of an A.P. is - 32 and the sum of
its eleventh and thirteenth term is - 94. Find the
common difference of the A.P. ​

Answer 1

Answer:

Step-by-step explanation:

a9= 32

i.e. a+8d = 32.......(1)

a11 +a13 = -94......(2)

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

2a + 22d = -94

Divide by 2

a + 11d = -47 .......(3)

Subtracting ,(1) and (3)

a + 8d =32

a+ 11d = -47

- - = +

-3d = 15

d = -5

Hence common difference is -5..

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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