Question

Given d=5 ,S9=75,find a and a9​

Answer 1

Answer:

here ur ans

d = 5 ,

S9 = 75

S9 = n/2[2a+(n-1) d

75 = 9/2[2a+(9-1) 5

(75*2) /9 = 2a+20

150/9 = 2a +20

150/9 -20 = 2a

(150-180) /9 = 2a

-10/9 = 2a

-10/9*2 = a

a = -5/9

a9 = a+8d

= -5/9 + 8 (5)

= -5/9 +45

= (-5+405) /9

= 400/9

hope it correct to u