Find-the-number-of-ways-to-choose-a-pair-a-b-of-distinct-numbers-from-the-set-1-2-3-50-such-that-i-a-b-5-ii-a-b-5-

Question Number 125207 by liberty last updated on 09/Dec/20

F i n d t h e n u m b e r o f w a y s t o c h o o s e a p a i r

{a, b} o f d i s t i n c t n u m b e r s f r o m t h e s e t

{1, 2, 3, \dots, 50} s u c h t h a t

(i) ∣ a - b ∣ = 5

(i i) ∣ a - b ∣ ⩽ 5

Answered by talminator2856791 last updated on 09/Dec/20

(i) 2 (45) = 90

(i i) 2 (5 (45) + 4 + 3 + 2 + 1)) = 470

Answered by john_santu last updated on 09/Dec/20

(i) 45

(i i) 235