7. Sum to n terms the series, whose nth term is 2^n + 3n -1.
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Answered by
9
ANSWER:
- The sum of n terms = n/2 ( 3 + 5n )
GIVEN:
- nᵗʰ term is 2ⁿ + 3n -1.
TO FIND:
- The sum of n terms
EXPLANATION:
Sₙ = n/2(2a + (n - 1)d)
a = 2¹ + 3(1) - 1 (since a is the first term)
a = 2 + 2
a = 4
d = t₂ - t₁
t₁ = a = 4
t₂ = 2² + 3(2) - 1
t₂ = 4 + 6 - 1
t₂ = 9
d = 9 - 4 = 5
Substitute a = 4 and d = 5 in Sₙ
Sₙ = n/2 ( 2(4) + (n - 1)5)
Sₙ = n/2 ( 8 + 5n - 5)
Sₙ = n/2 ( 3 + 5n )
Hence the sum of n terms = n/2 ( 3 + 5n )
Answered by
4
ANSWER:
The sum of n terms = n/2 ( 3 + 5n )
GIVEN:
nᵗʰ term is 2ⁿ + 3n -1.
TO FIND:
The sum of n terms
EXPLANATION:
Sₙ = n/2(2a + (n - 1)d)
a = 2¹ + 3(1) - 1 (since a is the first term)
a = 2 + 2
a = 4
d = t₂ - t₁
t₁ = a = 4
t₂ = 2² + 3(2) - 1
t₂ = 4 + 6 - 1
t₂ = 9
d = 9 - 4 = 5
Substitute a = 4 and d = 5 in Sₙ
Sₙ = n/2 ( 2(4) + (n - 1)5)
Sₙ = n/2 ( 8 + 5n - 5)
Sₙ = n/2 ( 3 + 5n )
Hence the sum of n terms = n/2 ( 3 + 5n )
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