Answer:
a
Step-by-step explanation:
the nth term of an arithmetic sequence is
[tex]u_{n}[/tex] = u₁ + (n - 1)d
given u₂₀ = 100 and u₂₅ = 115 , then
u₁ + 19d = 100 → (1)
u₁ + 24d = 115 → (2)
subtract (1) from (2) term by term to eliminate u₁
0 + 5d = 15
5d = 15 ( divide both sides by 5 )
d = 3
substitute d = 3 into (1) and solve for u₁
u₁ + 19(3) = 100
u₁ + 57 = 100 ( subtract 57 from both sides )
u₁ = 43
Answer:
a) u₁ = 43, d = 3
Step-by-step explanation:
Given :-
u₂₀ = 100
u₂₅ = 115
To Find :-
u₁ and d
Solving :-
u₂₀ = u₁ + 19d = 100 -(1)
u₂₅ = u₁ + 24d = 115 -(2)
(2) - (1)
5d = 15
d = 3
u₁ + 19(3) = 100
u₁ + 57 = 100
u₁ = 43
Solution :-
a) u₁ = 43, d = 3
