Question

ii) An=9-5n
S15=•••?

Answer 1

Hope it helps you:)

An=9-5n

putting n=1,a1=9-5(1) =4

a2 = 9-5(2) =-1

d=a2-a1 = -1-4=-5

S15=15/2{(2(4)+(15-1)-5}

=15/2(8+(-70)

Answer 2

HLO MATE HERE IS UR ANSWER

n = 1 , an = 9-5 《1》 = 4

a2 = 9-5 《 2》 = -1

d = a2 - a 1 = -1 -4 = -5

s15 = 15 /2 { 2 (4 ) + (15-1) -5}

15 /2 ( 8 + ( -70 )