Answer:
10. A possible value of missing term is -175 ⇒ last answer
11. The sum = 900 ⇒ first answer
Step-by-step explanation:
10. ∵ It is a geometric sequence
∴ The constant ratio between any two consecutive numbers is r
∴ r = x/35 and r = 875/x ⇒ x is the missing term
∴ x/35 = 875/x
∴ x² = (35)(875) = 30625
∴ x = ±√30625 = ± 175
∴ A possible value of missing term is -175
11. ∵ -10 , 0 , 10 , 20 , ........................ , 130 is arithmetic series
∴ Tn = a + (n - 1)d
a is the first term , d difference between any 2 consecutive terms
n is the position of the number in the series
∴ Sn = n/2(a + L) ⇒ L is the last term
∵ a = -10 , d = 10 , L = 130
∴ 130 = -10 + (n - 1)(10)
∴ 130 + 10 = 10(n - 1) ⇒ 140 = 10(n - 1)
∴ 140/10 = n - 1 ⇒ 14 = n - 1 ⇒ n = 14 + 1
∴ n = 15
∴ S(15) = 15/2 [-10 + 130] = 15/2 (120) = 900
