Question

The general term of a sequence is given by a n = -4n + 15 . Is the sequence forming an AP? If so find its 15th term and the common difference.

Answer 1

Hey buddy here is your answer !!!

an = - 4n + 15 also 15 - 4n
an = a + ( n - 1 ) d
a1 = 15 - 4 × 1 = 15 - 4 = 11
a2 = 15 - 4 × 2 = 15 - 8 = 7
a3 = 15 - 4 × 3 = 15 - 12 = 3

AP : 11 , 7 , 3

sn = n/2 { 2a + (n-1) d }
sn = 3 / 2 { 2 × 11 + (3-1) -4
sn = 3 /2 { 22 + 2 × - 4 }
sn = 3/2 { 22 + (-8) }
sn = 3/2 { 22 - 8 }
sn = 3/2 × 14
sn = 3 × 7
sn = 21

Hence Sn = 21



Hope u make my answer as brainalist one

Answer 2

Answer:

hope this answer useful to you mate