Question

in an AP if a= -15, an= 1, Sn= -63, then n is equal to?

Answer 1

Answer:

• a + (n-1)d = an

• -15 + (n-1)d = 1

• (n-1)d = 16

• n[2a + (n-1)d]/2 = Sn

• n[-30 + 16]/2 = -63

• -14n = -126

• n = 9