Question

7th term of an AP is17 and its 17th term is 7 . what is the common difference?,Find 24th term.,What is the sum of first 47terms?,what is the sum of first 48 terms?​

Answer 1

Step-by-step explanation:

tn=a+(n‐1)d

t7=a+(7‐1)d

a+6d=17- let it be equ-1

t17=a+(n‐1)d

a+(17‐1)d

a+16d=7...let it be equ 2

Now subtracting 1 from 2 ...u get

a+16d‐(a+6d)=7‐17

a+16d‐a‐6d=‐10

10d=‐10

d=‐1

Substituting d in equ 1 or 2 u get

a+6(‐1)=17

a‐6=17

a=23

Sn= n/2[2a+(n‐1)d]

S47= 47/2[2(23)+(47-1)(-1)]

S47=47/2[46-46]

S47=47/2×0

S47=0

S48=48/2[2(23)+(48-1)(-1)]

S48=24[46-47]

S48=24(-1)

S48=-24

HOPE IT HELPS